LABORATORY COURSE 
IN 
HISTOLOGY 
BY 
ADOLPH ELWYN, A.M. 
* n 
Assistant Professor of Anatomy, College of Physicians and 
Surgeons, Columbia University 
AND 
OLIVER S. STRONG, Ph.D. 
Associate Professor of Neurology, College of Physicians and 
Surgeons, Columbia University- 
NEW YORK 
PHYSICIANS AND SURGEONS BOOK COMPANY 
353 West 59th Street 
1920 COPYRIGHT, 1920 
BY 
PHYSICIANS AND SURGEONS BOOK COMPANY 
Copyright, Great Britain. All Rights Reserved PREFACE. 
The directions here printed represent essentially an out- 
line of the laboratory work in histology, including the 
minute structure of the nervous system, given at the Col- 
lege of Physicians and Surgeons, Columbia University, 
N. Y. They are. based almost entirely on the permanent 
study collections which are loaned to the student for the 
academic year. The instructions are in the main directive, 
though a certain amount of description has been introduced 
where the complexity of the section makes necessary an 
orientation of the structures. Such description has been 
found of greatest value in the difficult sections of the nerv- 
ous system. As a whole the directions are intended to enu- 
merate- to the student the more important structural feat- 
ures, while their detailed study is left to his own initiative. 
Questions have been introduced for the purpose of 
stimulating the student to supplement and interpret the 
structures studied in the laboratory. 
The histology of the nervous system has assumed such 
large proportions, that in this college, as well as in many 
others, a separate course is devoted to it. It is for this 
reason that the nervous part has been placed separately, 
forming the second part of the syllabus. The directions 
cover the microscopic work of the course in neuro-anatomy. 
In order to facilitate the introduction of special sections 
or fresh material, blank pages have been provided, so that 
the student may note down changes or additions to the 
laboratory work made by the instructor. In this way the 
III IV 
Preface. 
book is made more adaptable to courses in other institu- 
tions, whose teaching material may differ from ours. 
It is hoped that this book will economize the time of 
both student and instructor. The latter will thereby be 
able to devote more time to informal and individual teach- 
ing, and to the discussion of topics which he may deem of 
especial interest or importance. 
Adolph Elwyn, 
Oliver S. Strong. 
August, 1920. CONTENTS. 
CHAPTER I. 
The Cell 1 
A. Cell Structure 1 
B. Cell Division 3 
C. Cytomorphosis 5 
PAGE 
CHAPTER II. 
Early Development 7 
A. The Sex Elements 7 
B. Maturation and Fertilization 9 
C. Cleavage, Blastula Formation 11 
D. Gastrulation. Germ Layers 11 
E. The Vascular System 19 
F. The Nervous System 19 
CHAPTER III. 
Epithelium •. 23 
A. Simple Epithelium 23 
B. Stratified Epithelium 25 
CHAPTER IV. 
The Connective Tissues 29 
A. Connective Tissues Proper 29 
B. Cartilage 33 
C. Bone 35 
CHAPTER V. 
Muscle Tissue 39 
A. Smooth Muscle 39 
B. Striated Muscle 39 
C. Cardiac Muscle 41 
CHAPTER VI. 
Blood and Lymph 43 
V VI 
Contents. 
CHAPTER VII. 
The Circulatory System ... 47 
PAGE 
CHAPTER VIII. 
The Lymphoid Organs ■ 53 
Serous Membranes 55 
CHAPTER IX. 
The Alimentary System ' 57 
A. Headgut and Appendages 57 
B. Foregut, (Esophagus and Stomach 59 
C. The Small Intestine 63 
D. The Large Intestine 65 
E. The Large Glands of the Alimentary System 67 
CHAPTER X. 
The Respiratory System 75 
CHAPTER XI. 
The Urinary System 79 
CHAPTER XII. 
The Reproductive System 83 
A. Male Reproductive Organs 83 
B. Female Reproductive Organs 85 
CHAPTER XIII. 
The Placenta 93 
CHAPTER XIV. 
The Skin and Appendages 97 
CHAPTER XV. 
The Endocrin Glands 103 
CHAPTER XVI. 
Nervous Tissue 109 
A. The Neurone: Neurone Body 109 
B. The Neurone: The Nerve Fiber 115 
C. Secondary Degeneration of Nerve Fibers 121 
D. Secondary Degeneration in Neurone Body 123 Contents. 
VII 
PAGE 
E. "Primary" Degenerative Changes in Neurone Body 127 
F. Regeneration of Nerve Fibers 127 
G. Effect of Nerve Injury on Striated Voluntary Muscle 127 
H. Peripheral Terminations of Nerve Fibers 129 
I. Neuroglia; Structure of Gray and White; Meninges 131 
CHAPTER XVII. 
The Nervous System 137 
A. General Arrangement of the Peripheral Nervous System.. 137 
B. Spinal Cord: Histogenesis and General Arrangement of 
Neurones 139 
C. Spinal Cord: General Topography and Arrangement of 
Fibers 145 
D. Spinal Cord: Cell Groups 151 
E. Spinal Cord: Fiber Tracts 155 
F. Rhombencephalon: Medulla, Pons, Cerebellum, Isthmus.. 167 
G. Mesencephalon 207 
H. Prosencephalon: Diencephalon, Telencephalon ' 213 
CHAPTER XVIII. 
The Organs of Special Sense 229 CHAPTER I. 
THE CELL. 
A. Cell Structure. 
1. Epithelium from skin of onion mounted in normal NaCl 
solution. 
Study with low and high power. Note size, shape and 
arrangement of cells. Identify nucleus, nucleolus, cytoplasm, 
cell wall. Study carefully character of nucleus and cytoplasm, 
and draw several cells showing parts seen. 
2. Make a similar study of a thin slice of the potato. Note 
especially the thick cell wall and the starch granules. What 
is the shape of the latter? Are they part of the living cyto- 
plasm? Sketch several cells. 
3. Section of starfish ova. 
Select good cell and study with high power. Note size and 
shape of cell, nucleus, cytoplasm and cell membrane. Is the 
latter as well defined as in the epithelium of the onion? Make 
out the following structures: 
In nucleus-Nuclear membrane. 
Nuclear sap (karyolymph). 
Chromatin and linin. 
Nucleolus (plasmosome). 
In cytoplasm-Hyaloplasm. 
Spongioplasm. 
Cell inclusions (metaplasm), consisting 
here almost entirely of yolk. 
Ectoplasm and endoplasm. How do they 
differ? 
Make careful high power drawing, labelling all parts. 
4. Dissociated liver cells from salamander. 
Study with high power. Note the large spherical nuclei 
imbedded in cytoplasm. Is a definite cell membrane present? 
Compare with starfish ovum and onion cells. In nucleus 
identify nuclear membrane, nuclear sap, linin and chromatin. 
The chromatin granules are often aggregated into larger 
masses (chromatin knots, karyosomes, false nucleoli) which 
must be distinguished from the true nucleoli (plasmosomes). 
Are there any karyosomes in the cells under observation? In 
cytoplasm note again hyaloplasm and spongioplasm. Cell in- 
clusions such as fat and glycogen may be present. Draw 
several cells. 
1 MEMORANDA The Cell. 
3 
5. Study and draw demonstration preparations showing 
mitochondrial filaments and mitochondrial granules. Are 
these part of the living cytoplasm? What is their general 
significance ? 
6. Study and draw demonstrations of astral system in the 
segmenting or maturing egg of some invertebrate. Note the 
centrosome, centrosphere and astral rays. 
7. Cell inclusions. Pigment. 
Study pigmented cells from retina. Note shape and ar- 
rangement of cells, and the rod-shaped pigment granules 
which pack the cytoplasm. The clear spots in the center 
represent the unstained nuclei. Sketch several cells. Study in 
the same way pigmented cells from choroid, and note the 
round pigment granules. Sketch. 
8. Cell inclusions. Zymogen granules. 
Study preparations of salivary glands or pancreas. Note 
the numerous granules in the distal part of the cell. Are the 
granules of the same size? Are they part of the living cyto- 
plasm, or products of cell metabolism ? Sketch a few cells 
showing shape of cell, position of nucleus and secretory 
granules. 
9. Cell inclusions. Fat. 
Study fat cells in derma of skin or subcutaneous tissue. 
These are large oval cells consisting of a peripheral rim of 
cytoplasm, enclosing a large unstained area which in the living 
state is occupied by fat globules. The nucleus is situated at 
the periphery surrounded by a small amount of cytoplasm and 
gives to the cell a signet ring appearance. Sketch a few cells. 
10. Section through various organs of salamander. 
Review of cell structure. Select various types of cells and 
study briefly, identifying as far as possible structures studied 
above. Do the cells vary in size, shape and cytoplasmic make- 
up? Note especially the shape and structure of the nucleus 
and its position in the cytoplasmic mass. 
B. Cell Division. 
1. Section through tip of growing onion or hyacinth root 
to show mitosis (karyokinesis). 
Study carefully with high power, find and draw the 
following stages: 
1. Cell with nucleus in resting condition. 
2. Nucleus with close spireme. 
3. Nucleus with open or loose spireme. 
4. Segmented spireme. MEMORANDA The Cell. 
5 
5. Arrangement of chromosomes in equatorial plane 
(monaster). 
6. Metakinesis. Chromosomes show longitudinal split- 
ting. Often hard to find and should be seen in 
demonstration. 
7. Diaster. Several stages in the migration of the 
daughter chromosomes derived from the longi- 
tudinal splitting, to the poles of the cell. 
8. Several stages showing reconstitution of the daughter 
nuclei, the daughter nuclei first forming an open 
and then a close dispireme. 
9. Daughter cells with reconstituted nuclei (in resting 
condition). 
At which of the above stages does cytoplasmic division 
begin? How does cytoplasmic division take place? Is the 
nuclear membrane present in all the stages? When does it 
disappear? When reappear? Answer the same questions with 
regard to the nucleolus. If possible, make out achromatic 
spindle. Centrosomes have not been demonstrated in the 
higher plants. 
2. Study demonstration of mitosis in animal cell with es- 
pecial reference to astral system (centrosome, centrosphere, 
amphiaster). 
3. Study preparation of living yeast cells mounted in 
Ringer's solution, and sketch several cells in the process of 
amitotic division. Compare with demonstration showing ami- 
totically dividing animal cells (bladder cells, cells of epididy- 
meal duct). Which is the most common type of cell division? 
What is the significance of mitosis? 
C. Cytomorphosis. 
1. Section of skin from finger tip. 
Select representative cells from each of the several layers 
of epidermis, study carefully with high power and draw. Note 
the changes that take place in the shape of the cell and the char- 
acter of the nucleus and cytoplasm as you go from the inner- 
most layer to the surface. What is meant by cytomorphosis ? MEMORANDA CHAPTER II. 
EARLY DEVELOPMENT. 
A. The Sex Elements. 
1. Section of starfish ova. 
Review structure of ova studied at a previous exercise, 
identifying parts enumerated before. What is the shape of the 
cell? Its comparative size? How are the deutoplasmic (yolk) 
granules distributed? What is their significance? 
2. Human ovary. Study of ovum (primary oocyte). 
Find ovum in Graafian follicle and study with low power. 
Note the nucleus cytoplasm, peri vitelline cleft and zona pellu- 
cida. (The ovum is surrounded by follicular cells, the inner- 
most layer of which forms the corona radiata). As in pre- 
vious slide, identify the various structures in nucleus and cyto- 
plasm. Is the nucleus rich in chromatin? Are yolk granules 
present? If so, how distributed? Is there a differentiation 
into ectoplasm and endoplasm? To what type does the human 
ovum belong, judging from amount and distribution of yolk 
present? Make careful drawing. 
3. Study ovum of frog. Compare with human ovum re- 
garding size, shape, position of nucleus, amount and distri- 
bution of yolk. What is meant by the following terms: 
meiolecithal, mesolecithal, polylecithal, isolecithal, telolecithal, 
centrolecithal ? 
Note.-The importance of the yolk granules can hardly be 
overestimated. Yolk represents stored up food stuff contain- 
ing the elements necessary for the growth of the embryo.. In 
addition, it exerts in a purely physical way a profound in- 
fluence on the growth of the embryo, as will be seen in subse- 
quent studies. 
4. Living spermatozoa from guinea pig. 
Under low power there will be seen in the fresh prepara- 
tion numerous flagellated cells in rapid movement. Occasion- 
ally a cluster of spermatozoa may be seen moving in a unit. 
Study with high power. When movement has slowed down or 
ceased, make out the acrosome (perforatorium), head, body 
and tail of the spermatozoa, noting carefully the shape and 
relative size of each. Find spermatozoa showing profile view. 
The head will appear flattened, the acrosome resembling a spur 
extending forward. Draw, showing face and profile views. 
7 MEMORANDA Early Developments. 
9 
5. Human spermatozoa. E5. 
These are extremely difficult to find owing to their minute 
size. A careful low power search will reveal a number of 
bluish granules. Study these carefully with high power. Each 
granule has a small filament coming from it. This is the tail, 
the granule representing the nucleus of the head. Can you see 
a small amount of cytoplasm surrounding the nucleus? Is a 
middle piece (body) discernible? How does the human sperm 
compare in size with that of the guinea pig? Draw. 
Note.-Compare the two sex elements wth regard to size 
and shape. With what function is the peculiar shape of the 
sperm associated? What is the significance of the voluminous 
cytoplasm of the ovum ? As far as you know, is the chromatin 
content of the two sex elements correspondingly modified? 
B. Maturation and Fertilization. 
1. Maturation of Ascaris ova. 
The scattered ova of the thread-worm Ascaris present 
a number of stages of the maturation process. In this species 
the maturation divisions take place after the entry of the 
sperm. The latter (male pronucleus) will be recognized as 
a dark granule in the interior of the cytoplasm. Find, study 
and draw the following stages: 
Tetrad stage. How many tetrads present? How different 
from ordinary chromosomes? 
First maturation spindle. 
First polar body (dyad stage). 
Second maturation spindle. 
Second polar body. 
Male and female pronuclei. Are chromosomes disting- 
uishable ? 
What is the numerical relation of tetrads to the somatic 
chromosomes? What is the significance of the polar bodies? 
Are polar bodies formed during spermatogenesis? 
2. Spermatogenesis (grasshopper, salamander, mouse). 
Study demonstration preparation showing spermatogonia, 
primary spermatocytes, primary spermatocyte division, second- 
ary spermatocytes, secondary spermatocyte division, sperma- 
tids, and spermatozoa in several stages of development. Com- 
pare the process of maturation in the sperm and ovum. Is the 
process, essentially the same in both? What are the main 
differences? 
Note.-What types of maturation are recognized? Char- 
acteristics of each type? General significance of maturation? MEMORANDA Early Developments. 
11 
3. Study demonstrations showing fertilization of sea urchin 
ovum, noting entry of sperm, approach of the two pronuclei, 
formation of astral system, and nuclear changes during first 
segmentation division. How is the amphiaster formed? 
C. Cleavage, Blastula Formation. 
1. Cleavage of sea-urchin and starfish ova. 
Study several slides showing cleavage stages from 2 cell 
stage to late blastula and draw a representative series. Is 
cleavage complete? Equal? How many layers of cells in the 
wall of the blastula? 
2. Cleavage of frog ova. 
The specimens represent 32 cell stages in vertical section. 
Study with ocular and low power. Are the blastomeres of the 
same size? Are the pigment granules equally distributed? 
Which are micromeres and which macromeres? Which the 
animal and which the vegetal pole? What type of cleavage 
is shown? The small cavity in the interior of the egg is the 
segmentation cavity. Draw, showing all parts. Under high 
power note large amount of highly refractile yolk granules in 
macromeres. Is yolk present in micromeres? 
Note.-How does the yolk afifect the process of cleavage? 
How are eggs classified as to their yolk content? To what 
class does the starfish egg belong? That of the frog? What 
are the so-called "laws" of cleavage? How do they explain 
longitudinal and latitudinal division? 
3. Blastula of frog, vertical sections. 
Study with ocular and low power. The wall of the blastula 
shows a thinner roof consisting of pigmented micromeres, and 
a thicker floor consisting of macromeres containing a large 
amount of yolk granules. The yolk cells extend mound-like 
into the eccentrically placed segmentation cavity. Note care- 
fully the marginal zone, transitional between micromeres and 
macromeres. This is a region of great importance in the sub- 
sequent stages. Compare blastula of starfish and frog. Draw, 
showing parts studied. Under high power study briefly the 
distribution of pigment and yolk granules. Can you see the 
cell boundaries of the micromeres? of the macromeres? 
D. Gastrulation. Germ Layers. 
1. Section through gastrula of frog. 
Study with ocular. Select gastrula with opening in ecto- 
derm through which the pale staining cells of the yolk plug 
protrude. The opening is the blastopore. The gastrula con- MEMORANDA Early Developments. 
13 
sists of an outer more pigmented layer (ectoderm), and an 
inner less pigmented layer (entoderm). The entoderm is thin 
on one side, but much thicker on the other side where it be- 
comes continuous with yolk plug. The cavity enclosed by the 
entoderm is the archenteron (primitive gut). Low power. 
The ectoderm is seen to consist of several layers of pigmented 
cells of the yolk entoderm protrude through the blastopore 
derm becomes continuous with the thin entoderm (protento- 
derm) forming the roof of the archenteron. Follow the pro- 
tentoderm and note its merging with the heavier mass of yolk 
entoderm which forms the floor of the archenteron. Some 
cells of the yolk entoderm protrude through the blastopore 
forming the yolk plug. Does the ectoderm of the ventral lip 
become continuous with the entoderm, as in the dorsal lip? 
How do you explain this difference, if any? In many cases 
two cavities will be seen separated by a thin layer of yolk cells 
(the completion plate). The rupture of this completion plate 
will unite the original archenteron with the segmentation cavity 
still remaining, producing a more spacious archenteron. Note 
that the blastoporal lips are greatly thickened, consisting of a 
solid mass of cells. These cells form the anlage of the peris- 
tomial mesoderm. Make careful drawing showing all parts. 
Note.-How does gastrulation in frog differ from that of 
Amphioxus? How is this difference explained to a large ex- 
tent? Does the gastrula of the frog already show evidence of 
bilateral symmetry? If so, locate the anterior, posterior, dor- 
sal and ventral sides of the embryo. 
2. Transverse section of frog embryo. Late stage in for- 
mation of neural tube. 
Study with ocular and low power. The outline of the em- 
bryo is symmetrical except on the dorsal side where an eleva- 
tion appears due to the developing neural tube. The ectoderm 
consists of several layers of deeply pigmented cells. Note the 
medullary folds and medullary groove (or canal if the folds 
have fused). Is the ectoderm continuous with the medullary 
(neural) plate? From what germ layer is the neural tube 
derived? The archenteron is surrounded by entoderm, thin 
dorsally but forming a heavy mass ventrally. Note the char- 
acter of the entodermal cells immediately lining the enteric 
cavity. The mesoderm is the layer between ectoderm and 
endoderm. Is it sharply demarcated from the two primary 
layers? On the sides of the neural tube the mesoderm is 
thickened to form the primitive somites (segments) of the 
embryo. The oval mass of cells directly underneath the neural 
tube and between the two somites is the notochord (chorda). MEMORANDA Early Developments. 
15 
Is there any evidence of a coelomic cavity? Make careful 
drawing, labelling all parts. 
Note.-Distinguish between peristomial and gastral meso- 
derm. Compare chorda and mesoderm formation with that of 
amphioxus. 
3. Chick embryo of about 27 hours incubation. Section 
through region of primitive streak. 
Low power study. The blastoderm appears as a narrow 
band in the middle portion of which may be seen the three 
germ layers. Note the sharp notch on the ectodermal surface 
where the three layers are fused. This is the primitive groove, 
and the fused layers underneath constitute the primitive streak. 
Trace ectoderm along its entire extent and note that toward 
the end of the section it rests upon the yolk (stained black). 
Trace entoderm. Does it extend laterally as far as the ecto- 
derm? The zone where it merges with the yolk is the germ 
wall. Trace mesoderm in similar fashion. Where does it 
end ? Drawing. With high power study primitive streak re- 
gion noting shape and arrangement of cells in the three layers. 
Draw. Trace the layers to germ wall. Compare ectoderm of 
this region with that of primitive streak. Are nuclei present 
in the yolk mass? Note that near the entoderm the yolk 
granules are smaller than near the end of the section. Can 
you explain this fact? Study mesoderm cells of this region. 
Does mesoderm extend farther laterally than entoderm. Draw 
portion of germ wall region. 
Note.-It must be kept in mind that the germ layers are 
spread out flat on large yolk mass, from which they were re- 
moved previous to preparation. The space underneath the 
entoderm between left and right germ wall is the archenteron. 
When viewed from above that portion of the blastoderm cover- 
ing archenteron appears translucent and is called the area 
pellucida. The surrounding portion of the blastoderm appears 
opaque and is called the area opaca. 
4. Chick embryo of about one day incubation. Section 
through various regions of embyro. 
Study representative sections from anterior, middle and 
posterior regions of embryo. How can you identify region 
of primitive streak? What are the main differences in sections 
anterior to primitive streak? Sketch section through cranial 
region. 
5. Chick embryo (about 36 hours incubation). 
Compare with (4). Note ectoderm extending on each side, 
mvaginating medullary plate and medullary groove, notochord, 
and entoderm extending from germ wall to germ wall. Meso- MEMORANDA Early Developments. 
17 
derm forms a definite somite on each side of notochord. 
Laterally somite is continuous with a narrower portion the in- 
termediate cell mass (nephrotome). Lateral to nephrotome 
mesoderm splits into parietal and splanchnic layers. What is 
the cavity enclosed by these layers? Where does cavity end? 
Trace parietal and visceral layers.? In the latter numerous 
spaces are seen containing cells. These are blood-vessels with 
included blood cells. The two thin walled vessels lying ventral 
to the somites are the dorsal aortse. 
High power. Study and compare cells making up the fol- 
lowing structures: Neural plate, non-neural ectoderm, meso- 
dermic somites, nephrotome, parietal and visceral layers of 
mesoderm, entoderm. How far does ectoderm extend ? Meso- 
derm? Delimit area pellucida, area opaca. 
6. Chick embryo (about 42 hours incubation). 
Low power. Compare with (5) and identify same struc- 
tures as before. What main changes have taken place? Note 
the large number of blood-vessels found in visceral layer of 
mesoderm. Under high power note carefully the nature of 
tissues composing the various structures studied. Make care- 
ful outline drawing and fill in details. What is meant by 
somatopleure? splanchnopleure ? Is there any evidence of 
amnion formation? 
7. Chick embryo (about 62 hours incubation). 
Study under low power and compare with (6). Identify 
the neural tube, notochord, dorsal aortae. Ventral to the noto- 
chord is seen an inverted groove due to the convergence of the 
opposite splanchnopleures. This is the intestinal groove and 
is lined by entoderm. Note that a short distance from the 
midline the somatopleure (ectoderm and parietal mesoderm) 
bends sharply ventrad forming a groove. This is the lateral 
sulcus which delimits the body of the embryo from the extra- 
embryonic portion of the germ layers. Trace remainder of 
somatepleure. Identify amnion, chorion. Of what layers 
does each consist? Identify amniotic cavity, extra-embryonic 
coelom. Study the mesodermic somite. Note its differentia- 
tion into narrower epithelial bands, the myotome or muscle 
plate, and a larger mesial portion, the sclerotome, consisting 
of more loosely arranged tissue. Is there any evidence of a 
cavity (myoccele) in the somite? To what other cavity 
studied is this homologous? The nephrotome (intermediate 
cell mass) has enlarged and bulges into coelom. In it identify 
the post-cardinal vein, the kidney duct (mesonephric duct) and 
mesonephric tubules. Make large low power drawing showing 
parts studied. Emphasis should be laid on proper proportion 
2 MEMORANDA Early Developments. 
19 
of parts. Study is facilitated by tracing separately each germ 
layer. As in previous slide study various structures under 
high power noting the nature and arrangement of its cellular 
make-up. 
E. The Vascular System. Early Development. 
Note.-Most of the following slides have been studied be- 
fore. They are now reviewed with especial reference to the 
vascular system. 
1. Chick embryo (about 27 hours incubation). 
Identify mesoderm. A short distance from primitive 
streak there may be seen in mesoderm clumps of cells. These 
blood-islands are the earliest anlages of blood-vessels and blood 
tissue. Study cells under high power. Revise earlier drawing. 
2. Chick embryo (about 36 hours incubation). 
Identify dorsal aortse. Study blood-vessels in visceral layer 
of mesoderm. Note endothelial lining and included primitive 
blood cells. Are all the blood cells detached from the' endo- 
thelial wall? Explain. All these blood-vessels belong to the 
vitelline circulation. 
3. Yolk sac of chick. 
Note again blood-islands in mesoderm (close to entoderm). 
Are any blood-vessels present? Compare with (2). 
4. Chick embryo (about 42 hours incubation). 
Study and compare with (2). What changes have taken 
place? 
5. Heart of chick (about 42 hours incubation). 
Locate neural tube, notochord, dorsal aortae. Note shallow 
foregut cavity ventral to notochord. Below the foregut is the 
tubular heart. Note the inner endothelial, and outer meso- 
thelial wall. How has the heart been formed? What is the 
dorsal mesocardium? From what part of this primitive heart 
does the latter musculature (myocardium) develop? The part 
of the coelom surrounding heart is the pericardial cavity. The 
lateral sulcus and early amniotic folds are shown in this speci- 
men. Drawing of complete embryo. 
6. Demonstration of models showing complete circulation 
of early chick embryo. 
F. The Nervous System. 
Note.-The following slides are reviewed with especial ref- 
erence to the nervous system. Revise drawings previously 
made. MEMORANDA Early Developments. 
21 
1. Chick embryo of one day incubation. 
Select section through primitive axis (anterior to primitive 
streak). Note neural plate, neural groove, neural folds. Of 
what tissue is neural plate composed? 
2. Chick embryo, about 36 hours incubation. 
Identify same structures as in previous slide. What 
changes have taken place? 
3. Chick embryo, about 42 hours incubation. 
The neural tube has been formed. The walls are thick, 
the roof and floor plates thinner. What is meant by neural 
(ganglionic) crest? Is it seen in this specimen? Explain 
the presence of the skin ectodermal layer dorsal to the neural 
tube. 
4. Chick embryo, about 62 hours incubation. 
Note the relative thickness of walls, floor plate and roof 
plate. A shallow furrow (sulcus limitans) along each side of 
central canal divides each lateral wall into a dorsal (alar) and 
ventral (basal) plate. Under high power examine region out- 
side of neural tube on its dorso-lateral surface. Groups of 
large cells may be seen invading the region of the sclerotome. 
These are cells migrating from the neural crest, and form the 
rudiments of the spinal ganglia. 
5. Pig embryo (20 mm.). 
Note that the neural tube is completely surrounded by 
mesenchymal tissue. The wall of the neural tube exhibits 
three well marked areas, an inner (nuclear) layer, a middle 
(mantle) layer, and an outer (marginal) layer. What is the 
significance of these layers? Is a sulcus limitans visible? Out- 
side of neural tube identify: spinal ganglion, dorsal root, 
ventral root, spinal nerve, ramus communicans, sympathetic 
ganglion. Discussion of specimen at time of study. Draw, 
showing all parts seen. MEMORANDA CHAPTER III. 
A. Simple Epithelium. 
1. Simple squamous epithelium (mesothelium) from mes- 
entery of rabbit. 
Select small area and study with high power. Note shape 
of cell, irregular serration of cell borders, position and shape 
of nucleus. Draw small area. 
2. Stomach (or intestine). 
A layer of simple squamous epithelium (mesothelium) 
lines the outer surface of the stomach and intestine. Note 
flatness of the cells, and the oval bulging nuclei. Draw small 
strip. 
3. Simple squamous epithelium (endothelium) from pia 
mater. 
With high power study carefully the lining of the smaller 
blood-vessels. Compare with preceding slides. Note that the 
long- axis of the endothelial cell is parellel with that of the 
blood-vessels. Sketch. 
4. Endothelium from blood-vessels of skin. 
Select small blood-vessel shown in cross-section and study 
endothelial lining. Sketch. 
5. Study simple squamous epithelium in alveoli of lung. 
How does it differ from endothelium and mesothelium studied 
above ? 
6. Synovial membrane. 
The epithelium lining synovial membranes is sometimes 
called a false epithelium. It consists of an epithelioid arrange- 
ment of connective tissue cells. The cells may appear as 
simple squamous or low cuboidal. Which type is present in 
your specimen? Draw small strip. 
7. Organs of salamander. Simple columnar epithelium. 
Find columnar epithelium of intestine and study with high 
power. Note shape and arrangement of cells, position and 
shape of nuclei and character of cytoplasm. Note delicate 
basement membrane separating cells from the underlying tis- 
sue, and the thickened cuticular border of the free surface 
(distal border). Draw. 
EPITHELIUM. 
23 MEMORANDA Epithelium. 
25 
8. Study epithelial lining in stomach and small intestine, 
making out structures mentioned on previous slide. Compare 
the size of the cells with those of salamander. Compare cutic- 
ular border in stomach and intestine. Draw several cells. 
9. Kidney of guinea pig. Cuboidal epithelium. 
Study some of the cuboidal cells in the straight tubules. 
Note the regular outline of the cells, the shape and position of 
the nucleus. How may these cells be distinguished from 
squamous epithelium? from high columnar? 
10. Liver. 
With high power study carefully the polyhedral (cuboidal) 
epithelium of the liver. Note the general shape of the cell, the 
large vesicular nucleus and the cytoplasmic inclusions (glyco- 
gen granules and fat droplets). The cells are arranged in 
columns and the cell outlines are difficult to distinguish. Draw 
small area. 
11. Submaxillary. Pyramidal (glandular) epithelium. 
The secreting tubules of most glands are lined by cells of 
pyramidal form (a modification of columnar or cuboidal 
epithelium). The clear cells, whose protoplasm is unstained, 
are mucous cells. Study carefully and draw. The purplish 
staining granular cells are serous cells. Note the coarse 
granules toward the free end of cell, and clearer zone of 
ergastoplasm toward base of cell. Draw several cells. Com- 
pare with mucous cell. 
12. Small intestine. Goblet cells. 
Some of the columnar cells of the epithelium become 
mucous secreting cells (goblet cells). Study with high power 
and draw several stages in the development of one of these 
cells. 
13. Study ciliated columnar cells isolated from epithelium 
of trachea. Note shape of cell, position of nucleus, cilia and 
basal granules. Draw. 
B. Stratified Epithelium. 
1. (Esophagus. Stratified squamous epithelium. 
With high power find purplish staining inner border which 
comprises epithelium of oesophagus. Make careful high power 
study, noting the basement membrane, the shape of the cells, 
the shape and position of the nuclei, and the character of the 
protoplasm, in the various layers of the epithelium. Draw 
narrow strip through entire layer. MEMORANDA Epithelium. 
27 
2. Study stratified squamous epithelium in thick skin. 
Compare with oesophagus. Study carefully cells from the 
deeper layers, noting especially the intercellular bridges. What 
is the probable function of the latter? Draw a few cells. 
3. Transitional epithelium from ureter or bladder. 
Study under high power and compare with stratified 
squamous epithelium with regard to thickness of membrane 
and shape of cells. Why is it called transitional? Draw strip 
through entire thickness. 
4. Study stratified columnar epithelium lining the caver- 
nous portion of the urethra and compare with the other types 
studied. Draw strip. 
5. Pseudo-stratified (stratiform) epithelium from trachea. 
Find epithelial lining of trachea and study with high power. 
Note shape and arrangement of cells, broad basement mem- 
brane, cilia and basal granules. (The superficial columnar cells 
of this type of epithelium are nearly always ciliated.) Is this 
a true stratified epithelium ? Draw narrow strip. MEMORANDA CHAPTER IV. 
THE CONNECTIVE TISSUES. 
A. Connective Tissues Proper. 
1. Pig embryo (14 mm.). Mesenchyme (embryonal con- 
nective tissues). 
Select area of loosely arranged tissue and study with high 
power. Note the loosely packed cells whose processes anas- 
tomose to form a network (syncytium). The spaces between 
the cells are filled with a clear fluid ground substance (matrix). 
Draw a small area, showing shape, structure and syncytial 
character of cells. (Mesenchyme is the mother tissue from 
which all the types of adult connective tissue are formed.) 
2. Umbilical cord of foetal pig. 
Study the embryonal (mucous) connective tissue, noting 
the shape and arrangement of the cells and the nature of 
the intercellular substances. Are fibrils present in the latter? 
Draw small area. 
3. Umbilical cord of 7 months foetus. Mucous connective 
tissue. 
Select area near periphery and study with high power. 
Compare with preceding slide, especially with regard to form 
of cells, and character and quantity of intercellular substance. 
Draw small area. 
4. Areolar (fibro-elastic) connective tissue from sub-cutis. 
Study with low and high power. Note the small number 
of cells and large amount of intercellular substance consist- 
ing of clear matrix, collagenous and elastic fibers. The col- 
lagenous fibers are arranged in wavy bundles. Do the bundles 
anastomose ? The elastic fibers are stouter, run singly and may 
branch, forming a wide-meshed network. The cells are but 
vaguely indicated by the stain. Find, if possible, the following 
types: Lamellar cells (ordinary connective tissue cells), 
plasma cells, mast cells. Draw, showing all parts seen. 
5. Areolar (loose fibrous, fibro-elastic) connective tissue 
from skin. 
As before note the large amount of intercellular substance. 
The cells are scattered and recognized mainly by their nuclei, 
the cytoplasm having shrunk during preparation. Note the 
clear matrix and the pink staining wavy bundles of collagenous 
fibers. Can you see any elastic fibers? How do you explain 
their seeming absence ? Examine various portions of the con- 
nective tissue on the slide, and note the varying density of 
29 MEMORANDA The Connective Tissues. 
31 
fiber arrangement. Note especially condensation of connective 
tissue around blood-vessels and glands. What is the prob- 
able explanation? Draw small area. 
6. Study demonstration preparation showing elastic fibers 
in areolar connective tissue of skin. 
7. Inactive mammary gland. 
Study the fibrous connective tissue and compare with pre- 
vious slide. Note the more compact arrangement of the inter- 
cellular substance. 
8. Ovary of 10 year old child. 
The fibrous connective tissue of the ovary is exceptionally 
cellular. Study with high power. Note the close arrange- 
ment of the connective tissue nuclei, and the collagenous fibers 
in the intercellular substance. Draw small area. 
9. Muscle and tendon. Dense white fibrous connective 
tissue. 
The tendon is seen in longitudinal section, and may be dis- 
tinguished from the muscle by its lighter stain. Study with 
high power. Note densely packed collagenous fibers arranged 
in parallel rows to give tensile strength. The ground substance 
is scanty and the cells few in number. Study shape and ar- 
rangement of cells. Draw. 
10. Elastic connective tissue from Ligamentum nuchae of 
elephant. 
Study with high power. Note the coarse elastic fibers 
surrounded by a small amount of fibrous connective tissue in 
which may be seen the nuclei of connective tissue cells. Draw 
transverse and longitudinal section. 
11. Adipose (fat) tissue from skin. 
Adipose tissue is a modified type of areolar tissue. Under 
low power fat appears as groups (lobules) of large ring-like 
cells, fibrous connective tissue separating the lobules, and to a 
less extent the individual cells. Sketch, showing lobule and 
connective tissue investment. Study and draw a few cells 
under high power noting the thin layer of cytoplasm, the 
nucleus, the intercellular connective tissue and the small blood- 
vessel. Be sure to distinguish the nuclei of the intercellular 
connective tissue from those of the fat cells. Explain the ring- 
like appearance of the cells. 
12. Developing fat from foetal pig. 
The fat globules are stained black by osmic acid. Find and 
draw several cells in different stages of fat formation. MEMORANDA The Connective Tissues. 
33 
13. Reticular connective tissue from lymph node. 
In the lighter portion of the specimen will be found a deli- 
cate pale staining reticulum, showing flat stellate cells at the 
intersections of the anastomosing fibers. Study carefully and 
draw small area. What is the relation of the cells to the 
fibers? Note the great number of dark staining cells (lympho- 
cytes) found in the meshes of the reticulum. These must be 
carefully distinguished from the cells of the reticular tissue. 
The reticular tissue plus the enmeshed lymphocytes is known 
as lymphoid tissue. Draw small area of lymphoid tissue. 
14. Pigmented connective tissue from choroid of ox. 
Study and draw several cells showing shape and arrange- 
ment of cells and character of pigment. 
15. Cornea of rabbit, to show relation of cells in connective 
tissue. 
Two specimens will be found on slide. The silver nitrate 
preparation shows the cell spaces clear and intercellular sub- 
stance dark. The lighter gold chloride preparation shows the 
converse of the first picture. No details of structure are seen. 
Study shape of cells with high power. Do the cells anasto- 
mose? Sketch several cells. 
B. Cartilage. 
1. Hyalin cartilage from trachea. 
Low power study of complete plate of cartilage. Note 
homogeneous matrix, shape and grouping of cells, cell capsules 
and perichondrium. High power study of central and per- 
ipheral portions of plate and of perichondrium. Note the 
transition from the cartilage to the fibrous connective tissue of 
perichondrium, the cell groupings, lacunae, capsules and hya- 
lin matrix. Can you find any blood-vessels in the cartilage? 
Draw strip from central portion through perichondrium. 
2. Elastic cartilage from dog's ear. 
Find cartilage plate and study with high power. Note the 
dense network of interlacing elastic fibers permeating the 
matrix. Compare with hyalin cartilage regarding shape and 
grouping of cells, lacunae, perichondrium, and presence of 
blood-vessels. Sketch strip including portion of perichon- 
drium. 
3. Fibro-cartilage from intervertebral disk. 
Study with high power. Note the small number and ar- 
rangement of the cells, and the dense fibrous tissue (collagen- 
ous fibers) filling the matrix. Is a perichondrium present? 
How does it differ from hyalin or elastic cartilage? From 
tendon? Draw small area. 
3 MEMORANDA The Connective Tissues. 
35 
4. In 14 mm. pig embryo study condensed mesenchymal 
tissue in region of future rib or vertebra. This tissue repre- 
sents a stage in the development of cartilage and is known as 
precartilage. Compare cell groupings with those of adult 
hyalin cartilage. Are capsules present? 
C. Bone. 
1. Ground bone sections, transverse and longitudinal. 
Study transverse section under low power. Note ,the 
haversian systems (haversian canal and concentric lamellae), 
interstitial lamellae, circumferential lamellae, lacunae. Examine 
haversian system under high power, identifying central canal, 
lacunae, carialiculi and arrangement of lamellae. What are the 
contents of the canal? of the lacunae? Why are the contents 
missing? What is the significance of the canaliculi? Study 
interstitial and circumferential lamellae. How do they differ 
from haversian systems? Find Volkman's canals of intersti- 
tial lamella, if present. What is their function? Examine 
longitudinal section and note, if possible, branching of haver- 
sian canals. Draw area (cross-section) including haversian 
system and interstitial lamellae. 
2. Femur of cat, decalcified, cross and longitudinal sec- 
tions. 
Study with low and high power identifying structures seen 
in previous slide. In addition, note periosteum, endosteum, 
bone cells in lacunae and perforating fibers of Sharpey. What 
is the significance of these fibers ? Draw narrow strip extend- 
ing from periosteum to endosteum. 
3. Spongy bone from transected rib. 
Low power study. Note the irregular bone trabeculae, 
which anastomose enclosing spaces in which the bone marrow 
is contained. Have the lamellae a definite arrangement, as in 
compact bone? 
4. Intramembranous bone development. Skull of human 
foetus.. 
With low power identify periosteal and endosteal regions, 
bone trabeculae, osteogenic tissue, osteoblasts. How are the 
latter arranged? Significance? Draw strip through bone. 
Under high power study carefully shape and arrangement of 
osteoblasts. What is their relation to the bone trabeculae? In 
the trabeculae are found numerous lacunae enclosing bone cells. 
How have these been formed? The loose tissue surrounding 
the trabeculae is osteogenetic tissue. How are the osteoblasts 
related to this tissue? Study the blood-vessels, especially with 
regard to size of lumen and thickness of wall. Compare vas- MEMORANDA The Connective Tissues. 
37 
cularity of developing bone with that of adult bone. From 
some of the trabeculae may be seen extending fine pink stain- 
ing spicules. These are calcified fibers. What part do they 
play in bone formation? Search your slide carefully and note 
the occasional presence of large multinuclear cells. These are 
the osteoclasts, and are usually found closely applied to the 
bone, often in a small indentation in the bone (Howship's 
lacuna). What is the significance of the osteoclasts? On 
what surface of the bone trabeculse are they usually found? 
Explain. Study carefully tissue of periosteum. Of what 
tissue does adult periosteum consist? Draw strip through 
whole of thickness of bone showing parts studied. 
5. Intracartilaginous bone development. Leg bones of pig 
embryo. 
Study with ocular and low power. Make out,- 
Shape of bone. 
Periosteum (or perichondrium). 
Center of ossification. In this region will be found 
osteogenetic tissue, osteoblasts, bone 'trabeculae, blood 
vessels and primary marrow spaces. In the trabeculae 
note the presence of degenerating cartilage cells and 
cartilage matrix. Explain their presence. Underneath 
the periosteum are elongated plates of bone, the sub- 
periosteal bone trabeculae. How are they formed? 
Compare with intramembranous bone. 
Center of calcification. Found on either side of the 
ossification area. Note especially shape and arrange- 
ment of cartilage cells. 
Normal cartilage. What type of cartilage is present? 
Make topography drawing of complete bone. Under high 
power study carefully the structure of the following parts: 
Osteogenetic tissue, structure and arrangement of osteoblasts, 
bone trabeculae with included lacunae and bone cells, blood- 
vessels. Are osteoclasts present? Study cartilage in area of 
calcification, and trace to normal cartilage. What changes 
have taken place in structure and arrangement of cells? Is 
the change from normal to calcified cartilage abrupt? Draw 
strip extending from normal cartilage to center of ossification 
and include periosteum. 
Note.-How does intramembranous differ from intracar- 
tilaginous ossification? To what class does sub-periosteal ossi- 
fication belong? How do long bones grow in length? in 
diameter? How is the marrow cavity formed? What is 
meant by spongy bone? MEMORANDA CHAPTER V. 
MUSCLE TISSUE. 
A. Smooth Muscle (Non-striated, Involuntary). 
1. Isolated smooth muscle cells from gizzard of chicken. 
High power study. Note shape of cell, position and shape 
of nucleus, myofibrils, sarcoplasm and delicate cell membrane 
(sarcolemma). Many cells should be examined until all ele- 
ments are identified. Draw several cells. 
2. Smooth muscle from stomach and intestine. 
With low power find area showing smooth muscle in cross 
and longitudinal section. 
High power study of fibers in longitudinal section. Note 
the elongated, rod-shaped nuclei, and arrangement of the fibers 
into muscular membrane. Sketch small area. 
High power study of cross-section fibers. Note arrange- 
ment of fibers and position of nuclei. Explain the varying 
diameter of the fibers, and the absence of nuclei in many of 
them. Draw small area. 
3. Umbilical cord of 7 months foetus. 
Study smooth muscle in the walls of the blood-vess.els. 
Can you find any intercellular cement? Intercellular bridges? 
Sketch a few cells. 
B. Striated Muscle (Voluntary). 
1. Teased striated muscle fibers. 
Select suitable muscle fibers and make careful high power 
study. Note the longitudinal fibrils (myofibrils), sarcoplasm 
and cell membrane (sarcolemma). Where the fibers have been 
crushed the sarcolemma may be easily seen spanning the 
break. Note the alternating dark (anisotropic) and light 
(isotropic) bands forming the cross striations of the fibers, 
Hensen's line (mesophragma), Krause's line (telophragma). 
Find some fibers which show a terminal cleavage into the 
constituent myofibrils. Draw portion of fiber showing parts 
seen. 
2. Stained striated muscle fibers. 
Two specimens will be found on slide. Study pink stained 
muscle fibers and note position, shape and number of nuclei. 
Compare with smooth muscle. Draw, showing myofibrils, sar- 
colemma, nuclei, dark and white bands. Can you see Hensen's 
39 MEMORANDA Muscle Tissue. 
41 
or Krause's lines? Study purple stained fibers and compare 
with above. 
3. Transected muscle of dog. 
Low power. Note arrangement of muscle fibers into 
bundles separated by connective tissue (perimysium), the con- 
nective tissue surrounding group of bundles (epimysium). 
Sketch. 
High power. Note the delicate connective tissue (endo- 
mysium) surrounding individual fibers. Make out sarco- 
lemma, myofibrils, sarcoplasm, structure and position of 
nuclei. What is meant by Cohnheim's areas? Draw several 
fibers in cross-section. 
4. (Esophagus. Upper end. 
Find and study striated muscle fibers in cross and longi- 
tudinal section. Compare with previous slides. 
5. Juncture of muscle and tendon. 
Study carefully termination of muscle fibers in tendon. 
What is the relation of the tendon fibers to myofibrils? to 
sarcolemma? Note the increased number of nuclei at level 
of junction. What is their significance? Draw. 
6. Demonstration of Purkinje fibers and atrio-ventricular 
bundle (bundle of His). 
C. Cardiac Muscle (Striated Involuntary). 
1. Teased isolated trabeculae (fibers) from macerated 
heart. 
Select lighter staining "fibers" and study with high power. 
Note irregular shape of fibers, position of nucleus, myofibrils, 
sarcoplasm, sarcolemma, cross striations. Sketch a few fibers. 
2. Ventricle of heart, transverse and longitudinal section. 
High power study. In longitudinal section note the branch- 
ing muscle trabeculae (fibers) forming syncytium. Note shape 
and position of nuclei, myofibrils, sarcoplasm, sarcolemma, 
cross striations, intercalated discs. Study transverse section 
and identify sarcolemma, myofibrils, sarcoplasm and nucleus. 
How may the cardiac muscle be distinguished from striated 
voluntary muscle? From smooth muscle? Significance of 
intercalated discs? Draw small area of fibers in transverse 
and longitudinal section. MEMORANDA CHAPTER VI. 
1. Fresh blood. 
With sterile needle, prick tip of finger or lobe of ear pre- 
viously sterilized with alcohol and allowed to dry. Mount 
small drop under cover slip and study immediately with high 
power. Note the fluid plasma (matrix) and the great num- 
ber of red blood corpuscles (erythroplastids, erythrocytes). 
What is their color when seen under high power? Study 
corpuscles in face and profile view, and note formation of 
rouleaux. Are the corpuscles nucleated? Sketch. After a 
while the plasma will become hypertonic due to evaporation, 
and corpuscles of shrunken irregular outline will appear 
(crenated corpuscles). Study and draw. Among the cor- 
puscles may be seen occasional leucocytes, which are colorless 
and glistening in appearance. 
2. As before mount drop of blood on slide under cover 
glass, and add drop of distilled water. Study under high 
power and note what changes have taken place. Explain. 
How do erythroplastids react to hypertonic and hypotonic 
solutions ? 
3. Mount drop of blood on slide and let dry. Add drop of 
distilled water and wait until it dries again. Study under 
high power the numerous hemoglobin crystals with regard to 
color, size and shape. Draw a few crystals. Why was the 
distilled water added? 
4. Stained blood smear. Study of leucocytes and blood 
platelets. Study with high power or oil immersion lens. Var- 
ious types of leucocytes will be found scattered among the 
numerous red blood corpuscles. Find, study and draw the 
following types: small lymphocyte, large lymphocyte, transi- 
tional (large mononuclear) leucocyte, polymorphonuclear 
neutrophilic leucocyte, eosinophilic leucocyte, basophilic leu- 
cocyte (mast cell) and blood platelets. (The eosinophiles and 
basophiles are relatively rare and slide should be carefully 
searched.) Compare the various types with regard to struc- 
ture of nucleus, size of cell, relative amount of cytoplasm 
and granular make-up of cytoplasm. What is the relative 
abundance of each type in normal blood? Are the blood plate- 
lets nucleated? What is their probable origin and function? 
BLOOD AND LYMPH. 
43 MEMORANDA Blood and Lymph. 
45 
5. Find blood-vessels in wall of stomach and intestine and 
study contents, identifying the various blood cells present. 
Sketch. 
6. Study contents of the chorionic blood-vessels of a pig 
embryo and note the nucleated red blood corpuscles. Are they 
all of the same size and shape? Sketch. 
7. Bone marrow. Smear preparation. 
Under low power note general cell mass, which seems to be 
riddled by numerous round or oval spaces. These spaces in 
the living marrow are filled with fat which has been extracted 
during preparation of slide. Study with high power or oil 
immersion lens and identify, if possible, the following cells: 
(a) Nucleated red blood cells (erythroblasts), (&) erythro- 
cytes, (c) myeloblasts or marrow cells (primitive blood cells), 
(d) various types of leucocytes, (^) giant cells (megakaryo- 
cytes and polykaryocytes). Is there any evidence of mitosis? 
Do you find any blood pigment? Significance? Note also the 
framework of reticular tissue. Draw cells of each type 
observed. 
What are the main foci of hematopoiesis in the embryo? 
In the adult? What is the probable origin of blood platelets? 
8. Study and draw the various types of blood cells in a 
smear preparation of lymph. Are red blood corpuscles pre- 
sent ? Blood platelets ? Does lymph coagulate ? MEMORANDA CHAPTER VII. 
THE CIRCULATORY SYSTEM. 
1. Blood-vessels from pia mater of bram. 
Under low power a number of small vessels may be seen. 
The thicker walled small arteries give off branches which be- 
come progressively smaller until the capillaries are reached, 
forming a network. The wall of a capillary consists of only a 
layer of endothelium. The capillaries converge to form small 
veins, which have a larger lumen and thinner wall than the 
corresponding small arteries. Draw, showing general arrange- 
ment and relative diameter of blood-vessels. Make also high 
power drawing of capillary, small artery and small vein. 
Identify the contents of the blood-vessels. 
2. Skin. 
In the derma (lighter stained portion) of the skin numer- 
ous blood-vessels are seen in transverse and longitudinal sec- 
tion. Find the following vessels, study with high power and 
draw: capillary, arteriole, venule, small artery, small vein. 
How does an arteriole differ from a capillary? from small 
artery? How may small arteries be distinguished from small 
veins ? 
3. Blood-vessels from pia mater. Silver nitrate prepara- 
tion. 
Study some of the capillaries with high power and note 
outline and arrangement of endothelial cells. What is the 
relation of the long axis of the cells to the long axis of the 
blood-vessel ? Sketch. 
4. Medium-sized artery and vein. 
Low power study. The artery may be recognized by its 
relatively smaller lumen and thicker wall. Note the corrugated 
inner surface and the three coats (intima, media, adventitia) 
forming the wall of the artery. Sketch. Study with high 
power and draw narrow strip through entire wall. Note en- 
dothelial lining, internal and external elastic (fenestrated) 
membranes and relative thickness of the three coats. Make 
similar study and drawings of vein. Compare artery and 
vein and note main differences. (The elastic fibers are un- 
stained and hence difficult to recognize. Their distribution 
will be seen on next slide.) 
47 MEMORANDA The Circulatory System. 
49 
5. Medium-sized artery and vein. Section showing elastic 
fibers. 
The elastic fibers are stained deep purple. Study artery 
and vein, noting the distribution of elastic fibers in each. In 
which coat are the fibers most abundant? Compare relative 
abundance in artery and vein. Draw small strip through wall 
of each vessel. 
6. Aorta. 
Two sections will be found on slide, the darker one show- 
ing elastic fibers in stained condition. Study carefully with 
low and high power. Note the relatively large intima, the 
very large media and the narrow adventitia. Compare with 
wall of medium-sized artery. Can you distinguish a definite 
internal and external membrane? Study carefully distribution 
of elastic fibers in the three coats, noting especially the great 
amount of elastic fibers among the muscle cells of the media. 
Draw strip through entire wall. 
7. Inferior vena cava. 
Study wall and note the large amount of longitudinally 
disposed smooth muscle cells in the adventitia. Compare with 
medium-sized vein. 
8. Study wall of umbilical arteries in umbilical cord. The 
wall consists of an inner longitudinal and an outer circular 
layer of muscle. Is elastic tissue present? Collagenous? 
Compare with umbilical vein on same preparation. 
9. Study demonstration preparation of a large cerebral 
vein, noting the almost complete absence of muscle tissue. 
Possible significance. 
10. Study small lymphatics (from skin, alimentary tract or 
lymph node). Compare with vein regarding thickness of wall 
and abundance of muscular and elastic tissue. Draw. 
11. In a similar manner study section of the thoracic duct. 
Identify the three layers and tissue composing each. Compare 
with vein. Draw. 
12. Heart, section through ventricle. 
Study carefully with low and high power. Identify endo- 
cardium, myocardium, epicardium. Of what tissue is each 
composed? Make low power sketch through whole thickness, 
and detailed drawing of portion of epicardium and endocar- 
dium. Compare structure of heart with that of artery or vein. 
What are chief differences? Similarities? 
4 MEMORANDA The Circulatory System. 
51 
13. Heart, section through mitral valve. 
Study carefully with low and high power. Note the nature 
of the endocardium lining both sides of the valve, and the 
fibro-elastic tissue between the two folds of the endocardium. 
Where is the elastic tissue most abundant? Is muscle tissue 
present? What type of muscle? How distributed? Signifi- 
cance ? Drawing of whole valve. MEMORANDA CHAPTER VIII. 
THE LYMPHOID ORGANS. 
1. Lymph node. 
Study with ocular and low power. Note the capsule and 
trabeculae of connective tissue extending into interior of node. 
Do they contain blood-vessels? Near the periphery (cortex) 
the dense lymphatic tissue is arranged in the form of lymph 
nodules with germinal centers, while the central portion is 
composed of irregular anastomosing lymph cords. Note the 
cortical and peripheral sinuses. What is their content ? Sketch 
entire node. Make high power drawing of strip including 
capsule, lymph nodule and portion of medulla. Are erythro- 
cytes present? What is the most characteristic type of cell 
found in node? 
2. Haemolymph node. - 
The main structure is similar to lymph node. Identify 
capsule, trabeculae, lymph nodules and lymph cords, sinuses. 
What is the content of the latter? How different from lymph 
node? Note also the numerous leucocytes and scattered 
masses of hemoglobin pigment. Significance? Is there any 
direct evidence of phagocytosis? Draw small area including 
part of sinus. 
3. Study preparation of hemolymph node showing endo- 
thelial lining of blood sinuses. 
4. Tonsils. 
Ocular and low power study, noting arrangement of lymph 
nodules, capsule, stratified squamous epithelium covering outer 
surface of tonsils and mucous glands. Do the nodules show 
germinal centers? Under high power note and sketch small 
area showing infiltration of stratified squamous epithelium 
with lymphocytes. 
5. Thymus of child. 
Study with ocular and low power. Note capsule and inter- 
lobular connective tissue dividing gland into more or less 
complete lobules. Sketch several adjacent lobules noting cor- 
tex and medulla in each lobule, and presence of Hassall's 
(thymic) corpuscles in medulla. Make high power sketch, in- 
cluding portion of cortex and medulla and Hassall's corpuscle. 
Distinguish latter from small blood-vessel. Compare structure 
of thymus with that of lymph node. 
53 MEMORANDA The Lymphoid Organs. 
55 
6. Spleen. 
With ocular and lower power note capsule, trabeculae con- 
taining blood-vessels, splenic corpuscles and splenic pulp. 
Sketch. Study with high power and draw strip including cap- 
sule, splenic corpuscle and-splenic pulp. Of what tissues is the 
capsule composed? How does the splenic corpuscle differ 
from an ordinary lymph nodule? The splenic pulp consists of 
diffuse lymphoid cords and intercordal venous sinuses, con- 
taining various types of blood cells. Identify the following 
cells: lymphocytes, erythrocytes, splenic cells (large mono- 
nuclear leucocytes). How may the spleen be distinguished 
from lymph nodes? from haemolymph nodes? 
7. Study preparation of spleen demonstrating the frame- 
work of reticular tissue. 
Serous Membranes. Synovial Membranes. 
1. Study pieces of mesentery mounted flat on slide and 
treated with silver nitrate. The serrated borders of the pave- 
ment epithelium (mesothelium) are clearly brought out. Are 
stomata present? Significance? Draw. 
2. Study section of diaphragm or of parietal peritoneum. 
Note the mesothelial lining and underlying connective tissue. 
Are lymphatics present ? Sketch. 
3. Study section of synovial membrane. What kind of 
cells line the inner surface. What kind of tissue beneath the 
epithelioid cells? Draw. 
Note.-The serous membranes are moistened by a lymph- 
like fluid and are often in direct connection with the lymphatic 
vessels by means of stomata. The synovial membranes are 
moistened by a fluid unlike lymph in character and they are 
included here only for convenience. MEMORANDA CHAPTER IX. 
THE ALIMENTARY SYSTEM. 
A. Headgut and Appendages. 
1. Section through entire thickness of lip. 
The lip is lined on both sides by stratified squamous epi- 
thelium forming the epidermis on the external surface. Com- 
pare epithelium on both sides regarding thickness and kera- 
tinization. Study connective tissue (dermis) below epidermis. 
Are hair follicles present? Sebaceous glands? Sweat glands? 
Blood-vessels? Study similarly connective tissue below epi- 
thelium of mucous membrane and note the numerous glands. 
What kind are they? Can you see their ducts? In center of 
lip note bundles of smooth muscle forming orbicularis oris 
muscle. Low power drawing through entire lip. 
2. Vertical section through tooth, undecalcified. 
With low power identify crown, neck, root, enamel, cement, 
dentine, pulp cavity and root canal. Sketch whole tooth. 
3. Study demonstration preparation of ground sections 
of tooth. Note the hexagonal prisms constituting enamel. In 
dentine find dentinal tubules? Significance? Study cement. 
Are lacunae present? Canaliculi? Compare structure of den- 
tine and cement with that of bone. 
4. Transverse section through root of decalcified tooth. 
Study pulp under high power, noting delicate connective 
tissue, blood capillaries and nerves. Near periphery of pulp 
find odontoblasts (close to dentine). What is their relation 
to the dentinal tubules ? Are lacunae present in the dentine ? 
Sketch showing pulp and dentine. 
5. Section through head of pig embryo. Anlage of tooth. 
Find oral epithelium, dental groove, dental lamina. Of 
what does the latter consist? Draw. 
6. Section through head of pig showing late stage of tooth 
development. 
Study with low power and identify (a) enamel organ con- 
sisting of outer enamel cells, enamel pulp and inner enamel 
cells, (b) enamel, (c) dentine, (d) odontoblasts, (^) dental 
papilla (future pulp). From what layer is the dentine de- 
rived? the papilla? the enamel? With high power make out 
detailed Structure Of various parts and draw narrow Qtn'n 
Are blood-vessels found in papilla? 
57 MEMORANDA The Alimentary System. 
59 
7. Tongue, section vertical to dorsal surface. 
The tongue is essentially a muscular organ. Study with 
ocular and low power. Note the thick stratified squamous 
surface epithelium covering irregular projections of the un- 
derlying fibrous connective tissue. These projections together 
with the covering epithelium form the papillae of the tongue. 
Below the mucosa (epithelium and underlying connective tis- 
sue) note large amount of striated voluntary muscle.' Com- 
pare the relative amount of muscle and connective tissue. In 
mucosa identify filiform and fungiform papillae. How do they 
differ? Explain the absence of circumvallate papillae. Study 
distribution of striped muscle, noting the longitudinal trans- 
verse and vertical arrangement. Make topographical (low 
power) drawing showing features seen. Are there any glands 
in the tongue? 
8. Circumvallate papillae from tongue. 
Study with low power and draw, noting secondary papillae, 
trench surrounding papilla, and the serous glands of Ebner 
with their ducts. What type of glands are these? Can you 
find any taste-buds? 
B. Foregot, (Esophagus and Stomach. 
Note.-The wall of the alimentary tract and many other 
tubular structures consists of four coats. From within out- 
ward these are (1) mucosa (mucous membrane), (2) sub- 
mucosa, (3) muscularis, (4) fibrosa or serosa. 
The mucosa consists of a layer of epithelium (often form- 
ing glands which may or may not extend into submucosa), 
a layer of delicate connective tissue {stroma, tunica propria) 
containing the finer blood-vessels and nerves, and a thin layer 
of smooth muscle called the muscularis mucosa; (not always 
present). 
The submucosa comprises coarser connective tissue, con- 
taining the larger blood-vessels and nerves. The submucous 
plexus of Meissner is found in this layer. 
The muscularis consists usually of two layers of smooth 
muscle, an inner circular and outer longitudinal. In the con- 
nective tissue septum between the two layers, is found the 
myenteric plexus of Auerbach. 
The fibrosa consists of fibrous connective tissue containing 
blood-vessels and attaching tube to surrounding structures. 
The serosa (serous membrane) consisting of fine fibrous tis- 
sue and a layer of mesothelium, takes the place of fibrosa 
where the tube or organ extends into the coelomic cavity. MEMORANDA The Alimentary System. 
61 
The above represents a fundamental but general plan of the 
structure of the alimentary wall. The individual modifica- 
tions of the various parts will be noted as they are successively 
studied. 
1. CEsophagus, upper end. 
With ocular and low power identify the four coats-mu- 
cosa, submucosa, muscularis, fibrosa. Note the stratified 
squamous epithelium resting on the stroma. Is a muscularis 
mucosae present? Note the presence of solitary lymph nod- 
ules in stroma. What kind of glands, if any, are found in 
submucosa? In muscularis find inner and outer layer of 
muscle. How is each disposed? What type of muscle is 
represented? Note character of fibrosa. Make topography 
drawing of narrow strip through entire thickness. Is this a 
transverse or longitudinal section. 
2. CEsophagus, lower end. 
Study and compare with previous slide, noting especially 
changes in muscular coat. What is the distribution of the 
two varieties of muscle (smooth and striped) in the oeso- 
phagus ? 
3. Juncture of oesophagus and stomach from dog. 
Study oesophageal portion identifying parts studied before. 
Note especially the abundance of mucous glands in submucosa, 
and type and arrangement of muscle in muscularis. Com- 
pare with man. Study zone of juncture with stomach. Is the 
change from stratified squamous to simple columnar epithe- 
lium abrupt or gradual? 
4. Stomach, region of fundus. 
Ocular and low power. Identify the four coats, noting 
presence of serosa with its mesothelial lining. Note the 
temporary ridges (rugae). What coats are involved in their 
formation? Note the minute depressions (gastric pits) on 
surface of mucosa. The submucosa is especially rich in blood 
vessels. Are there any glands in submucosa? Compare with 
oesophagus. In muscularis note inner oblique, middle circular 
and outer longitudinal layer. Is the muscle of smooth or 
striped variety? Topography drawing. 
High power study of mucosa. Study epithelium of the 
surface of the mucosa, the gastric pits and gastric glands. 
Select glands in longitudinal section. Make out neck, body 
and fundus of gland, chief and parietal cells. What is the 
shape and distribution of latter? Find gland in transverse 
section, noting again the chief and parietal cells. Note the 
presence of diffuse lymphoid tissue and solitary lymph nod- MEMORANDA The Alimentary System. 
63 
ules in greatly reduced stroma. Is a muscularis mucosae 
present? Draw narrow strip through mucosa, showing detail 
of structures studied. 
5. Stomach. Transition from fundus to pylorus. 
Study with ocular and low power. How does the mucosa 
of the pylorus differ from that of fundus, and is the transi- 
tion abrupt or gradual? Make high power study of pyloric 
gland and compare with fundus gland. Note the deep gastric 
crypt and nature of cells in body and fundus. Are parietal 
cells present? Enumerate main differences between fundic 
and pyloric glands. Sketch gland. 
C. Midgut. 
1. Juncture of stomach and duodenum. Longitudinal 
section. 
Study duodenum with low power, identifying four coats 
and comparing with pylorus part for part. In duodenum note 
the following: 
(a) Villi, how do they differ from gastric pits? 
(&) Intestinal glands (crypts of Lieberkuehn). 
(c) Duodenal glands (Brunner's glands) mainly in 
submucosa. 
(J) Valvulae conniventes (Plicae circulares). What 
coats are involved in their formation? How do 
they differ from rugae in stomach? (The valvulae 
are poorly shown in this specimen.) 
(^) Submucosal plexus of Meissner, and myenteric 
plexus of Auerbach. These will be found in same 
relative location throughout gastro-intestinal tract. 
How does the duodenum differ from pylorus? Is transi- 
tion abrupt? Topography drawing of duodenum. With high 
power study cross-sected tubules of Brunner's gland, noting 
the character of epithelium. What type of gland is it? How 
distributed? Draw. 
2. Jejunum. 
Low power study of general topography. Note the mucosa, 
submucosa, muscularis and serosa. Note the tall valvulae con- 
niventes and compare with duodenum. In mucosa note 
slender leaf-shaped villi, crypts of Lieberkuehn, muscularis 
mucosae, isolated lymph nodules. In submucosa note blood- 
vessels, adipose tissue, and find plexus of Meissner. Do you 
find any Brunner's glands in jejunum? The muscularis is 
typical, consisting of inner circular and outer longitudinal 
muscle. Between the two layers find plexus of Auerbach. 
Examine the structure of serosa, the mesothelial lining of MEMORANDA The Alimentary System. 
65 
which is often torn away. Is this a transverse or longitudinal 
section ? Make topography drawing showing strip through en- 
tire wall. 
High power study of mucosa. Study villus in longitudinal 
and transverse section. What layers are involved in its forma- 
tion ? Study epithelium noting the numerous goblet cells, and 
the striated cuticular border of the cells. The stroma contains 
connective tissue and lymph cells. Find, if possible, central 
lymph vessel (chyle vessel) and capillaries. Draw. Study 
crypt of Lieberkuehn, noting character of epithelium. In the 
fundus are found cells with coarse eosinophilic granules (cells 
of Paneth). What is their probable function? Draw. Is 
muscularis mucosae present? 
3. Small intestine of dog. Osmic acid preparation. 
Study epithelium with high power. Note the presence of 
minute fat globules (stained black) in the epithelial cells of 
the villi. In the stroma of the villus leucocytes will be found 
whose cytoplasm contains similar fat droplets. What signifi- 
cance is attached to the presence of fat in these cells? Note 
also the thick cuticular border, characteristic of the epithelium 
of the small intestine. Draw portion of villus showing 
features seen. 
4. Ileum. 
Study with ocular and low power. Note the aggregation 
of lymph nodules (agminated follicles) which form Peyer's 
patch. These nodules are structures of the mucosa but ex- 
tend secondarily into submucosa. What is their distribution 
in ileum ? In the mucosa they extend to the surface covered 
only by a layer of epithelium. Are villi present at those 
places? Note the breaking up of the muscularis mucosae 
where the nodules are encountered. The muscularis and 
serosa are typical. Make topography drawing including por- 
tion of Peyer's patch. 
Note.-Compare the three parts of the small intestine with 
regard to (a) nature and distribution of glands, (&) shape of 
villi and of valvulas conniventes (plicae circulares), (c) abun- 
dance and distribution of lymphoid tissue. 
D. Hindgut 
1. Colon. • 
Ocular and low power study. Is the section transverse or 
longitudinal? Are villi present? Valvulae conniventes ? Note 
the simple tubular glands extending to the muscularis mucosa, 
and the great number of goblet (mucous) cells. Are cells of 
5 MEMORANDA The Alimentary System. 
67 
Paneth present? Note the solitary lymph nodules. Are these 
confined to mucosa? Is muscularis muscosae well defined? 
The submucosa, muscularis and serosa are typical. Find again 
the nerve plexuses of Meissner and Auerbach. Topography 
drawing of strip through wall. High power drawing of gland. 
How does colon differ from small intestine? What are the 
lineae coli? Are they shown in the specimen? Explain. 
2. Vermiform appendix. 
Study with ocular and low power. Note the scattered 
simple tubular glands in mucosa. Compare epithelium with 
that of colon. The muscularis mucosa is broken up by the 
great abundance of lymph follicles which extend into sub- 
mucosa. The muscularis is well developed. Serosa typical. 
Topography drawing. 
3. Juncture of rectum and anus. Longitudinal section. 
Study with low and high power. Compare rectum and 
anus with regard to (a) type of epithelium, (&) arrangement 
of muscle tissue, (c) nature of glands. 
Low power drawing. 
4. Study demonstration preparations of stomach, small and 
large intestine showing distribution of blood-vessels in the 
various coats. 
E. The Large Glands of the Alimentary System. 
1. Submaxillary gland. 
Ocular and low power study. Note capsule and connective 
tissue trabeculae dividing gland into lobes and lobules. These 
trabeculae contain blood-vessels and the large ducts (inter- 
lobar and interlobular) which may be easily recognized by 
their regular columnar epithelium. Each lobule consists 
mainly of terminal secreting tubules, but contains also the 
intralobular ducts, small blood-vessels and connective tissue. 
Both serous and mucous secreting tubules are present, the 
former taking a purplish stain, the latter showing a practically 
clear cytoplasm. Which are more numerous? Make topog- 
raphy drawing of several lobules. 
High power. Study and draw interlobar and interlobular 
duct, noting type of epithelium, position of nuclei and char- 
acter of cytoplasm. Study intralobular (secretory) ducts, 
noting basal striations in cytoplasm. Significance? Draw. 
Study serous and mucous secreting tubules (acini) and com- 
pare with regard to shape of cell, position of nucleus, character 
and staining quality of cytoplasm. In serous tubule, note cen- 
tral granular zone and clearer basal zone. Around mucous MEMORANDA The Alimentary System. 
69 
tubule find demilunes of Heidenhain (crescents of Gianuzzi). 
What is their significance? Draw tubule of each type. What 
type of gland is the submaxillary? What is its duct system? 
2. Submaxillary of dog. Resting and stimulated. 
With low power note the relative abundance of mucous and 
serous tubules. Compare with man. Under high power study 
secreting tubule of resting and stimulated gland. How do they 
differ? Draw tubule in each stage. 
3. Study submaxillary of cat and note the large number 
of mucous tubules. How do demilunes compare with those of 
man ? 
4. Parotid gland. 
Study gland with ocular and low power noting as before 
general sub-division into lobes and lobules, interlobar and in- 
terlobular ducts, intralobular ducts and secreting tubules. Are 
mucous tubules present? With high power study and draw 
terminal tubule (acinus) and intermediate (intercalary) duct. 
Note coarse granules of the secreting cells. How are they 
distributed? Is the gland in resting or secreting condition? 
What is meant by parenchyma? Stroma? Compare duct 
system of parotid and submaxillary. 
5. Pancreas. 
Ocular and low power study. Note capsule and trabeculae 
of connective tissue, containing the larger (interlobar and in- 
terlobular) ducts and general mass of secreting tubules. Are 
they serous or mucous tubules? Among the tubules may be 
seen small oval or circular areas taking a lighter stain. These 
are the islands of Langerhans. Topography drawing. 
High power study terminal tubule (acinus). Note the 
shape of the cells and position of nuclei. In each cell two 
areas can be made out, a homogeneous (or finely granular) 
area containing nucleus, and a central area containing coarser 
zymogen granules. What is the significance of these granules ? 
Find, if possible, tubules containing centro-acinar (centro- 
tubular) cells. How is their presence explained? Can you 
find any intercalary (intermediate) duct? Draw tubule show- 
ing parts seen. Study islands of Langerhans, and make out 
the cords of anastomosing cells surrounded by capillaries. Do 
the cells contain zymogen granules? Are they connected with 
the duct system of the pancreas? What is the significance of 
the numerous capillaries? Draw islands of Langerhans. 
Study and draw portion of wall of interlobar or interlobular 
duct. What type of epithelium is present? What type of 
gland is the pancreas and what is its duct system? How may 
the pancreas be distinguished from, the parotid gland? MEMORANDA The Alimentary System. 
71 
6. Pancreas. Osmic acid preparation. 
The tubules are shown in outline, the cells containing 
zymogen granules. Draw tubule showing distribution of 
granules. 
7. Study and draw preparation of pancreas (guinea pig, 
rabbit) showing mitochondrial filaments. Possible significance 
of mitochondria? 
8. Liver. 
Under low power the specimen exhibits a great number 
of pink staining anastomosing bands or cords (liver cords) 
separated by lighter spaces, the liver capillaries (capilliform 
sinusoids). Closer inspection shows that the cords generally 
radiate from common centers and that the light spaces cor- 
respond in arrangement. Any one of these radial centers 
represents the cross-section of a lobule of the liver. Note that 
adjacent lobules are not separated by connective tissue, but 
that the cords of one lobule anastomose freely with those of 
another. This great reduction of interlobular connective tissue 
is characteristic of the human liver. (Compare with liver of 
pig, noting the connective tissue septa which divide the liver 
into distinct lobules.) Note that frequently in the center of 
the lobule there is a small opening (central vein, intralobular 
vein) from which the cords radiate. Frequently there will be 
seen between adjacent lobules, a vein, a small artery and small 
duct bound together by some connective tissue. These are 
respectively branches of the portal vein, hepatic artery and bile 
duct, and together with surrounding connective tissue consti- 
tute a "portal canal." On one side of the specimen may be 
seen a portion of the connective tissue capsule which invests 
the liver. Make topography drawing showing above features. 
Make high power study and drawing of liver "cords" and 
capillaries. Note type of epithelium, position and structure of 
nuclei and character of cytoplasm. How many rows of cells 
in a liver cord? Is there a definite cell membrane? What are 
the secreting tubules of the liver? Note the relatively large 
size of the capillaries and the endothelial lining wherever 
possible. Find the stellate cells of Kupfer. How do you ex- 
plain their presence? What is the relation of the capillaries 
to the liver cords ? Make also high power study and drawing 
of "portal canal." 
9. Liver, blood-vessels injected. 
Study blood supply of lobule with ocular and low power. 
Note the branches of the portal vein and hepatic artery, the 
intralobular capillaries converging to form central vein (intra- MEMORANDA The Alimentary System. 
73 
lobular vein) and sublobular vein. Make diagrammatic draw- 
ing of blood supply of lobule. Under high power note relation 
of capillaries to liver cells and the presence of intracellular 
(vascular) canaliculi. 
10. Liver. Silver nitrate preparation to show bile capil- 
laries. 
Select suitable lobule and study with low and high power. 
The fine dark brown or black lines are the lumina of the bile 
capillaries. Where are they situated ? Note that fine branches 
can be traced to the interior of the liver cells. Find, if pos- 
sible, juncture of bile capillaries with small bile duct. Draw. 
11. Liver of dog. 
Study with high power, noting the glycogen granules in 
the liver cells. Draw. 
12. Study section of liver treated with Scharlach R. and 
note presence of fat globules in liver cells. 
Note.-How does the liver differ in structure from the 
pancreas? Why is it called a tubulo-reticular gland? Com- 
pare the secreting tubules of the liver and pancreas with regard 
to type and arrangement of cells and blood supply. 
13. Gall bladder. 
With low power identify the various coats of the wall and 
note the irregular folds of the mucosa. High power study. 
What type of epithelium is present? Do you find lymphoid 
tissue? Glands? What type? How distributed? How is the 
muscle tissue disposed in the muscularis? Is the outer coat a 
serosa or a fibrosa? Topography drawing. MEMORANDA CHAPTER X. 
THE RESPIRATORY SYSTEM. 
1. Larynx. Longitudinal section. 
Study with low power. Identify the true vocal cords, the 
false vocal cords, the laryngeal ventricle, the thyroid and 
cricoid cartilages. Study with high power. What type of 
epithelium lines the true vocal cords? The remainder of the 
laryngeal surface? Of what tissue are the vocal cords com- 
posed? Is muscle tissue present? What kind? How dis- 
posed? In the submucosa note the presence of mucous glands 
especially in the region of the false vocal cords. Is lymphoid 
tissue found? Where most abundant? What is meant by 
laryngeal tonsil? Make low power drawing showing general 
topography of larynx. 
2. Trachea. 
Study with low power and verify details with high power. 
Identify the three coats (mucosa, submucosa, fibrosa). In 
mucosa note the stratiform ciliated columnar epithelium, the 
broad basement membrane, the stroma and elastic layer. Are 
goblet cells found in the epithelium? Is a muscularis mucosae 
present? What kind of glands are found in the submucosa? 
Where do they open? Note presence of cartilage plates in 
fibrosa. What type of cartilage? How disposed in trachea? 
Is this a transverse or longitudinal section? Draw strip 
through wall. 
3. Trachea. Transverse section. 
Identify same structures as before, and note the incomplete 
ring of cartilage. In the interval between the two ends of 
the cartilage find the smooth muscle tissue constituting the 
trachealis muscle. What type of muscle? How disposed? 
Sketch. 
4. Lung from dog. 
Study with ocular and low power. The specimen appears 
as a loose-meshed spongy mass in which are seen round or 
oval openings of definite outline and varying size (blood- 
vessels, larger and smaller bronchi, and bronchioles). The 
blood-vessels may be easily distinguished from the bronchi by 
their thin walls, endothelial lining and content (red and white 
blood cells). A thin pink staining band along one edge of the 
specimen is the visceral layer of the pleura. Note the large 
75 MEMORANDA The Respiratory System. 
77 
irregular spaces (infundibula, atria), each of which is sur- 
rounded by a number of small thin-walled compartments 
(alveoli). All of these alveoli communicate with the infundib- 
ula, though some alveoli appear as closed compartments, the 
section being above or below their level of communication. 
If possible find several infundibula in continuity with alveolar 
duct and terminal (respiratory) bronchioles. 
Note.-The continuity from small bronchus to terminal 
alveoli is as follows: Small bronchus, terminal (respiratory) 
bronchiole, alveolar duct, infundibulum with surrounding 
alveoli. These connections are hard to find on a thin section, 
but may often be traced after careful search. 
Make topography drawing showing pleura, general ar- 
rangement of blood-vessels, bronchi of various sizes, infundib- 
ula and alveoli. 
5. Lung. 
With ocular and low power briefly review structures seen 
in preceding slide. Make high power study and drawings of 
wall of large bronchus, small bronchus, and, if possible, of 
respiratory bronchiole. Compare with regard to character of 
epithelium, presence of muscularis mucosae, glands, and car- 
tilage plates. How does larger bronchus differ from small 
one?, from trachea? 
Study alveoli in tangential section and note the flat non- 
nucleated (respiratory) epithelium, among which are found 
low nucleated cells (foetal cells). What is the significance of 
the latter? Study the cross-sected walls of adjacent alveoli 
noting again respiratory and foetal cells. What intervenes 
between the walls of adjacent alveoli? Draw several alveoli. 
During breathing many dirt particles pass through trachea 
and bronchi, ultimately reaching alveoli. Find dust particles 
in alveoli or in connective tissue surrounding alveoli. What 
is the ultimate fate of this foreign matter? Give reasons for 
your conclusion. What type of a gland does the lung resemble 
morphologically ? 
6. Lung. Blood-vessels injected. With low power note 
larger blood-vessels (interlobular vessels) and dense capillary 
network around pink staining alveoli. Make high power 
drawing showing arrangement of capillaries around alveolus. 
What tissues intervene between blood in capillaries and air in 
alveoli ? 
7. Study and draw demonstration preparations showing 
distribution of elastic tissue around pulmonary alveoli. MEMORANDA CHAPTER XI. 
THE URINARY SYSTEM. 
1. Kidney of guinea pig. 
With naked eye note general outline, hilus, renal papilla 
pointing toward hilus and fitting into cup-shaped space (pel- 
vis). Outside of the kidney, near the pelvis, is seen a trans- 
verse section of the ureter. Under ocular and low power note 
the following parts: Capsule, cortex, medulla, papilla of 
medulla extending into pelvis. In cortex identify cortical 
labyrinths (cortical pyramids) and medullary (cortical) rays. 
Note that the kidney is packed with tubules in transverse and 
longitudinal section. In the cortical pyramids the tubules are 
convoluted and among them are found circular objects (the 
renal corpuscles). What is the direction of the tubules in 
medullary rays? In medulla the tubules run in a parallel 
radial fashion, forming the ducts of Bellini which open into 
the renal pelvis. Make topography drawing of whole kidney. 
Important Note.-The kidney is a compound tubular gland 
having a definite arrangement of tubules, which must be 
clearly understood. Following are the parts of a uriniferous 
tubule and their location in the kidney, given in the order of 
their succession: (1) Renal corpuscle, in cortical pyramid, 
(2) first (proximal) convoluted tubule, also in cortical pyra- 
mid, (3) descending arm of Henle's loop, passing straight 
down into medulla, (4) ascending arm of Henle's loop, extend- 
ing from medulla into medullary ray and thence back into 
cortical pyramid, (5) second (distal) convoluted tubule, again 
in cortical pyramid, (6) a small arched tubule emptying into 
(7) straight collecting tubule located in medullary ray. The 
straight collecting tubules converge to form (8) papillary ducts 
(ducts of Bellini) which run through medulla and open into 
the renal pelvis which is the dilated portion of the main ex- 
cretory duct (ureter). What is meant by simple kidney? To 
what type does human kidney belong? 
2., Kidney. Section vertical to surface. 
With ocular and low power locate capsule, cortex, medulla, 
cortical pyramids and medullary rays, noting direction of 
tubules in each. Make high power study of renal corpuscle, 
noting the double layer of the capsule (Bowman's capsule) 
and the glomerulus. Type of epithelium in Bowman's cap- 
sule? Find, if possible, renal corpuscle showing neck (leading 
to first convoluted tubule), and corpuscle showing afferent and 
79 MEMORANDA The Urinary System. 
81 
efferent glomerular vessels. Draw. Make high power study 
and drawings of first and second convoluted tubules, ascend- 
ing and descending arms of Henle's loop, arched tubule, 
straight collecting tubule and duct of Bellini. 
Where does the secreting portion of the tubule end, and 
excretory begin? How is this shown by the staining reactions 
of the two portions? In each part studied make out type of 
epithelium, cell outline, position of nucleus, character of cyto- 
plasm, and relative width of tubule. 
3. Kidney, tangential section. 
Study with low power. Explain why no portion of medulla 
is seen. How can you distinguish cortical pyramids from 
medullary rays ? Under high power identify and briefly re- 
view structures studied on previous slide. • 
4. Kidney, injected preparation. 
With ocular and low power note the arched arteries and 
veins shown in cross-section between medulla and cortex, 
cortical arteries and veins, medullary arteries and veins 
(straight vessels). Find renal corpuscle showing afferent and 
efferent glomerular arteries and glomerular capillaries. Under 
high power study and draw glomerulus with afferent and 
efferent vessels, and portion of capillary net among convoluted 
tubules. 
5. Study demonstration preparations showing shape and 
distribution of mitochondria in epithelium of convoluted 
tubule. 
6. Ureter. 
Study with ocular and low power. Note the three coats 
(mucosa, muscularis, fibrosa). What kind of epithelium in 
mucosa? How are the muscle cells disposed in muscularis? 
How would the muscularis differ in a more distal portion of 
ureter? Make topography drawing. 
7. Renal pelvis. 
Study wall and note its similarity to ureter. If possible, 
observe transition from simple columnar epithelium of papil- 
lary ducts to transitional epithelium of pelvis. 
8. Bladder. 
Study and compare with ureter with regard to (a) 
epithelium of mucous membrane, (&) presence of smooth 
muscle in muscularis, (c) presence of glands and lymph 
nodules. How does the epithelium of the collapsed bladder 
differ from that of the distended organ? Explain. Topog- 
raphy drawing. 
6 MEMORANDA CHAPTER XII. 
THE REPRODUCTIVE SYSTEM. 
A. The Male Reproductive Organs. 
1. Testis and epididymis. 
Study with naked eye and ocular. Identify testis proper, 
capsule of testis (tunica albuginea) and epididymis. The 
tunica albuginea is thickened on the flat side of the testis to 
form the mediastinum testis in which are located a number of 
irregular, anastomosing dark staining tubules, the rete testis. 
From the mediastinum connective tissue septa radiate into tes- 
tis dividing latter into lobules. The epididymis consists of 
fibrous connective tissue containing blood-vessels and tubules. 
The tubules with the irregular lumina are the vasa efferentia, 
those with regular lumina represent sections of the vas epidid- 
ymis. Review these structures with low power and note that 
the tunica albuginea has an inner vascular and an outer dense 
layer. Note also that the testis is packed with tubules (sem- 
iniferous tubules) cut in various planes and separated by in- 
terstitial tissue. Make topography drawing showing features 
studied. What type of gland is the testis morphologically? 
functionally? What represents its secreting portion? Enu- 
merate in order of their succession the various parts of the duct 
system of the testis. Make careful high power study of con- 
voluted seminiferous tubule in transverse section. Note the 
fibro-elastic connective tissue forming a more or less definite 
capsule, and the many-layered epithelium. Identify the var- 
ious spermatogenic cells-the basal layer of spermatogonia; a. 
few layers of primary and secondary spermatocytes; the small 
spermatids nearest the lumen; and the spermatozoa, either 
free in the lumen or with their heads embedded among other 
cells. How may the spermatocytes be distinguished from the 
spermatogonia? from spermatids? Note that many of the cells 
are in active mitosis. Among the spermatogenic cells may be 
seen some large pale nuclei belonging to the supporting cells 
of Sertoli. Note general character of stroina, find and study 
interstitial cells of Leydig. Significance of cells of Leydig? 
Draw strip through wall of tubule including some of the 
stroma and interstitial cells. 
Study carefully tubules of rete testis, vas efferens, vas 
epididymis, noting especially the nature of the epithelium. 
Draw, including in each case some of the surrounding tissue 
83 MEMORANDA The Reproductive System. 
85 
2. Vas deferens. 
Study with low power and note the various coats-mucosa, 
submucosa, muscularis and fibrosa. How many layers of 
muscle in muscularis? How disposed? Is the arrangement of 
muscle tissue the same along whole extent of vas deferens? 
Compare with ureter. Examine mucosa with low power and 
note type of epithelium. Topography drawing. 
3. Male urethra (corpus spongiosum). 
Study with naked eye, ocular and low power. Note mucosa 
surrounding irregular lumen, and broad submucosa containing 
reddish irregular patches (cavernous veins). Is there a defi- 
nite muscularis? Draw segment through entire wall. 
High power study. What kind of epithelium lining lumen ? 
Is the same epithelium found throughout urethra? What 
kind of tissue is found between cavernous veins? What is 
meant by erectile tissue? In mucosa find glands of Littre. 
What type of glands are they? Is a muscularis mucosa pres- 
ent ? Draw small strip of mucosa and gland of Littre. 
4. Penis. Transverse section. 
Study with ocular and low power. Identify the corpora 
cavernosa with their thick tunica albuginea, the corpus spon- 
giosum containing the urethra, and the integumentary en- 
velope. What forms the septum penis ? Are blood-vessels 
present? Where situated? Under high power study tunica 
albuginea of corpora cavernosa. Is elastic tissue present? 
Smooth muscle tissue? In corpus spongiosum make out the 
various coats of the urethra. Are glands of Littre seen? 
Topography drawing. 
5. Prostate. 
Note size and shape of alveoli and the abundance of muscle 
fibers in the connective tissue stroma. What epithelium lines 
the alveoli? The ducts? Do you find prostatic concretions 
(corpora amylacea) in the alveoli? What type of gland is the 
prostate? Draw alveolus and some of the surrounding fibro- 
muscular tissue. 
6. Study section of Cowper's gland (bulbo-urethral gland) 
noting especially (a) the epithelial lining of the alveoli, (&) 
the character and amount of muscle fibers in the stroma. 
B. The Female Reproductive Organs. 
1. Ovary of young girl. 
With naked eye and ocular note shape of organ, cortex 
and medulla. Note that the substance of the medulla is con- MEMORANDA The Reproductive System. 
87 
tinuous at the hilus with an irregular band of connective tis- 
sue extending some distance beyond ovary and containing 
numerous blood-vessels. This is the mesovarium by which the 
ovary is attached to the broad ligament. Under low power 
identify enveloping peritoneal layer (germinal epithelium), 
superficial capsule (tunica albuginea), cortex and medulla. 
The stroma of both cortex and medulla consists of richly 
cellular connective tissue, and contains blood-vessels. In cor- 
tex note (1) numerous primitive Graafian follicles, each con- 
sisting of a large pale staining cell (primary oocyte) and a 
layer of small (follicular) cells; (2) Graafian follicles in in- 
termediate stages of growth; (3) older Graafian follicles, 
identifying follicular cavity, stratum granulosum, germ hill 
(discus proligerus, cumulus oophorus) containing ovum, and 
the follicular capsule (theca folliculi). Make topography 
drawing. Study and draw under high power (a) Germinal 
epithelium. How does it differ from ordinary mesothelium? 
(&) Primitive follicle showing oocyte surrounded by a single 
layer of smaller follicular cells, (c) Follicle in intermediate 
stage of growth. Is a follicular cavity present? (d) Portion 
of older Graafian follicle including germ hill and theca folliculi. 
In germ hill note shape and structure of ovum, zona pellucida, 
corona radiata. What is the content of the follicular cavity? 
How is it formed ? How is the ovum extruded ? Of what 
tissue is the theca composed? Find and draw interstitial cells 
of ovarian stroma. What is their probable function? Com- 
pare with interstitial cells of testis. • 
2. Ovary of adult. 
Review structures seen in previous slide and note the pres- 
ence of corpora lutea and corpora albicantes. 
3. Corpus luteum. 
With ocular note irregular deep staining core, surrounded 
by pale convoluted band outside of which is a connective tissue 
capsule. Under low power note that capsule sends trabeculae 
to convoluted bands consisting of lutein cells. The central core 
is the remnant of blood clot (corpus hemorrhagicum) contain- 
ing blood cells, fibrin and some connective tissue. Topography 
drawing. Study and draw lutein cells under high power. 
What is the function of the corpus luteum? How does it 
develop ? 
4. Oviduct, section through ampulla. 
Study with ocular and low power. Note mucosa with its 
primary and secondary convolutions, muscularis and serosa. 
How many muscle layers? How distributed? What type of MEMORANDA The Reproductive System. 
89 
epithelium in mucosa? Are any glands present? Topography 
drawing. How do ova reach oviduct? 
5. Oviduct, section through isthmus. 
Study and compare with previous section regarding size 
of lumen and distribution of muscle tissue. How may the 
oviduct be distinguished from the ureter and the vas deferens? 
6. Uterus, section through body in resting condition. 
Under low power identify endometrium (mucosa), myo- 
metrium (muscularis) and perimetrium (serosa). What is 
the relative thickness of each? Tn myometrium identify, if 
possible, stratum submucosum, stratum vasculare and stratum 
supravasculare. How is the muscle tissue disposed in each of 
the layers ? Between the muscle fibers note the rich connective 
tissue stroma containing bood-vessels. Topography drawing. 
Study with high power and draw carefully strip through 
mucosa including a gland. Note the columnar ciliated epi- 
thelium of the surface (often the cells are cuboidal and non- 
ciliated), the basement membrane containing flattened cells 
and the cellular stroma. Study epithelium of gland and com- 
pare with surface epithelium. What type of gland? What 
type of secretion ? Significance of glands of the uterine body ? 
7. Uterus, longitudinal section through cervix. 
Identify endometrium, myometrium, perimetrium, cervical 
canal, vaginal portion and fornix. Study with high power. 
What kind of epithelium lines the surface? the vaginal por- 
tion and fornix? Study gland of cervix and compare with 
gland from body with regard to epithelium, length of gland 
and nature of secretion. What are Nabothian follicles? Are 
any seen in your specimen? What is their content? Draw 
cervical gland. 
8. Uterus, early menstrual period. 
Under low power identify the three coats and compare 
relative thickness of each with that of resting uterus.' Note 
that the surface epithelium, the superficial portion of the glands 
and outer portion of the stroma are destroyed. The deeper 
portion of endometrium likewise shows disintegration, the 
glands breaking down, the stroma ragged and containing a 
large number of red blood cells which have escaped from 
ruptured blood-vessels. Note that the glands are enlarged 
(hypertrophied), somewhat tortuous and broken; the vessels 
engorged with blood. Study carefully with high power and 
draw strip through mucosa. In myometrium note enlarged 
muscle fibers. What is meant by decidua menstrualis? MEMORANDA The Reproductive System. 
91 
9. Vagina. 
Under low power identify mucosa, submucosa, muscularis 
and fibrosa. What kind of epithelium in mucosa ? Any glands 
present ? In submucosa note sinus-like blood-vessels and mix- 
ture of connective tissue with muscle fibers, giving general 
character of "erectile tissue." What is arrangement of muscle 
fibers in muscularis? Topography drawing of strip through 
wall. How may the wall of the vagina be distinguished from 
that of the oesophagus? MEMORANDA CHAPTER XIII. 
1. Uterus and chorion of pig (simple type of placenta). 
Low power study. Identify chorion and uterine wall. 
Note that the chorion is thrown into folds or papillae which 
fit into corresponding depressions of the uterine mucosa, 
thereby achieving an intimate contact of the two surfaces. 
In foetal portion identify chorionic epithelium, amniotic epi- 
thelium and intervening stroma containing blood-vessels. In 
uterus identify the various coats noting especially the more 
regular distribution of muscle tissue in muscularis (compare 
with man). 
Under high power study carefully and draw strip through 
chorion and uterine mucosa. Type of epithelium lining chor- 
ion? Amnion? Uterine mucosa? Kind of tissue in chorionic 
stroma? Contents of chorionic blood-vessels. Compare with 
corresponding parts in uterine mucosa and explain differences. 
How does nutritive material from the mother reach the 
embryo ? 
2. Foetal placenta, two months. 
Under low power identify chorionic epithelium (tropho- 
derm), chorionic stroma and numerous villi in transverse and 
longitudinal section. In most specimens the trunk of a pri- 
mary villus is seen as an evagination from the chorion. In the 
intervillar spaces may be seen dense groups of cells (tropho- 
derm masses) and blood tissue. Explain the presence and 
source of each. Topography drawing. Under high power 
study and draw chorionic villus. The epithelium consists of 
an inner layer of regularly arranged cells (cyto-trophoderm) 
and an outer syncytial layer (plasmodi-trophoderm). Study 
nature and vascularity of stroma, and note type of blood cells 
in blood-vessels. Find cells of Hofbauer. What is their 
significance? Study and draw portion of trophoderm masses 
in intervillar spaces, noting size and shape of cells and presence 
of canalized fibrin. Significance of trophoderm masses and 
canalized fibrin? 
3. Foetal placenta, six months. 
Under low power identify again-amnion and chorion with 
intervening mesoderm core, villi, trophoderm masses and ma- 
ternal blood tissue in intervillar spaces. Can you distinguish 
between floating and fastening villi? Are decidual cells pres- 
THE PLACENTA. 
93 MEMORANDA The Placenta. 
95 
ent? Where found? Topography drawing. Study with high 
power and enumerate changes which have taken place in (a) 
chorionic epithelium. How many cell layers present? (&) 
Character of stroma, (c) Vascularity and contents of blood- 
vessels. Explain, (d) Amount of trophoderm masses and 
presence of canalized fibrin. Draw villus showing parts seen. 
Study and draw several decidual cells. How do you explain 
their presence? 
4. Maternal placenta, seven months. 
Study gravid uterus under low power and identify mucosa 
(endometrium) and muscularis (myometrium). A number of 
villi may be seen in close contact with mucosa. Note that the 
uterine epithelium has entirely disappeared. The stroma 
shows a superficial compact layer consisting mainly of decidual 
cells, and a deeper vascular layer containing blood-vessels and 
the atrophied uterine glands. Under high power study and 
draw strip through mucosa showing structure of decidual cells 
and character of uterine glands. Study myometrium and note 
the enormously enlarged muscle cells. Compare structure of 
resting, menstruating and gravid uterus. 
5. Study demonstration preparations showing section of 
complete placenta (maternal and foetal) and identify structures 
seen before. 
Note.-What is meant by chorion frondosum, chorion 
laeve, decidua basalis, decidua parietalis, decidua capsularis? 
Which of these structures enter into formation of the placenta ? 
How does exchange of material take place between the ma- 
ternal and foetal blood? What are the types of placenta found 
in mammals ? 
6. Umbilical cord. 
Identify amnion, stroma, umbilical vein and umbilical 
arteries. Study with high power. Nature of epithelium? of 
stroma? Is there any vestige of allantois or yolk sac? How 
do you explain the unpaired umbilical vein ? Compare wall of 
umbilical blood-vessels with that of normal arteries and veins. 
Enumerate main differential features. Low power drawing. MEMORANDA CHAPTER XIV. 
THE SKIN AND APPENDAGES. 
1. Skin from finger tip or palm of hand. Thick skin. 
With ocular and low power note the deeper staining epi- 
dermis, the dermis (corium) and the subcutis (tela subcu- 
tanea). In epidermis identify the various layers (stratum 
germinativum, stratum granulosum, stratum lucidum, stratum 
corneum), and note the spiral epidermal portions of the ducts 
of the sweat glands. In dermis identify (1) pars papillaris 
sending numerous papillae into germinative layer of epidermis; 
(2) pars reticularis containing coarser connective tissue, the 
larger blood-vessels and nerves. The subcutis consists of fat 
and loose connective tissue and in it are found the secretory 
portions of the sweat glands, nerve fibers in transverse or 
oblique section, and the concentric corpuscles of Pacini. Low 
power drawing through entire thickness. 
Under high power study and draw several cells from each 
layer of epidermis noting (1) shape of cell, (2) presence and 
position of nucleus, (3) granularity of cytoplasm, (4) visi- 
bility of cell outline. What process is illustrated? Are inter- 
cellular bridges seen? Where? Pigment granules? Where 
found? What is the lining of the epidermal portion of the 
sweat glands ? 
Study dermis and tela subcutanea. Find nervous and vas- 
cular papillae and draw tactile corpuscle of Meissner. Study 
and draw sweat gland. What type of gland? Nature of 
epithelium of secretory tubules and ducts? How does gland 
open to exterior? Study and draw Pacinian corpuscles, noting 
the protoplasmic core and the concentric layers of flattened 
epithelioid cells separated by seemingly structureless lamellae. 
2. Skin from negro. 
Study and draw strip of epidermis under high power, not- 
ing the distribution of melanic pigment granules. Compare 
distribution of such granules in white man and negro. 
3. Thin skin. 
Low power. Compare with thick skin. What layers are 
missing in epidermis? Is the dermis as papillated as in thick 
skin? In the derma may be seen occasional hair follicles in 
cross-section. Compare abundance of sweat glands in thick 
and thin skin. Where are they most numerous? Note oc- 
casional bundles of smooth muscle in dermis. What do they 
represent? Draw strip showing features seen. 
7 
97 MEMORANDA The Skin and Appendages. 
99 
4. Scalp.. 
Study with ocular and low power. As before, note epi- 
dermis and dermis with glands and blood-vessels. The strik- 
ing feature of this section is the presence of hair and the 
structures connected with it, the sebaceous glands and the 
arrector pili muscles. In hair, note shaft (projecting above 
the skin) and root which expands at its lower end into a knob- 
like enlargement, the hair bulb, enclosing the cup-like hair 
papilla derived from the corium. The root of the hair is 
enclosed by the follicle. Do the hairs come out perpendicular 
to the surface? What is the structure of the arrector pili? 
What is its function ? Find and study sebaceous gland. What 
type of gland? Where does it open? Topography drawing 
showing proper proportion of the parts. 
Under high power study suitable hair follicles (including 
hair) in transverse and longitudinal section. Note cortex, 
medulla and thin cuticle of hair. Make out the inner and outer 
root sheath of follicle. What is the derivation of the sheaths ? 
In inner sheath make out cuticle, Henle's layer, Huxley's layer 
and note structure of each. Of what type of cells is the outer 
root sheath composed? Note the outer connective tissue 
sheath identifying, if possible, the vitreous (glassy), vascular 
and fibrous layers. Draw follicle enclosing hair. Study area 
of transition from root and follicle to hair bulb. Are the 
various layers of the root sheaths distinct? Explain. Study 
carefully and draw sebaceous gland. What is its relation to 
the hair follicle? What type of gland? Epithelium of duct? 
of secretory alveolus? How is secretion formed? 
5. Nail. Longitudinal vertical section. 
Study with ocular, verify with low power. Identify nail 
body, nail root, nail fold, nail furrow. The horny epithelium 
of the nail fold is reflected over the nail body forming an ad- 
herent membrane, the eponychium. The under surface of the 
free portion of the nail is similarly invested by a horny mem- 
brane (the hyponychium) continuous with the epidermis of the 
finger tip. Note that the nail consists of two layers (1) a 
stratum lucidum continuous posteriorly with stratum lucidum 
of epidermis, but ending distally in a free margin; (2) a 
stratum germinativum continuous with similar layer of epi- 
dermis. Is there indication of a granular layer in any portion 
of the nail? Below the nail note the nail bed (corium, dermis) 
continuous with the corium of the skin. Is the nail bed vas- 
cular? Is it elevated into papillae? Low power drawing show- 
ing parts seen. Under high power study and draw strip 
through nail body and nail bed. MEMORANDA The Skin and Appendages. 
101 
6. Mammary gland, active. 
Under ocular and low power note the connective tissue 
trabeculae dividing gland into lobes and lobules, the interlobar 
and interlobular ducts, and the groups of terminal alveoli. 
Are blood-vessels present in connective tissue? Make low 
power drawing of several lobules including larger duct. 
High power study of alveolus. Note the simple cuboidal 
epithelium, and the great number of fat globules (unstained) 
found in the lumen. Are similar globules found in the cyto- 
plasm of the epithelial cells? Explain this fact. Note the 
greatly reduced inter-alveolar stroma containing spindle- 
shaped cells. Are blood-vessels present in the stroma? Ex- 
amine section of active mammary gland in which the fat 
globules are stained black by osmic acid. Note again the 
presence of fat globules in cell cytoplasm as well as in the 
lumen. Draw two adjacent alveoli. What type of gland is the 
mammary gland morphologically? How does secretion take 
place? What are colostrum corpuscles? At what period are 
they found in milk ? 
7. Mammary gland, inactive. 
Study with ocular and low power. How does it differ 
from active gland? Topography drawing. MEMORANDA CHAPTER XV. 
THE ENDOCRIN GLANDS. 
1. Thyroid gland. 
Under ocular and low power note capsule and connective 
tissue trabeculae dividing gland into incomplete lobules. Each 
lobule contains numerous alveoli, oval or irregular in shape, 
whose lumen is filled with a pink staining homogeneous sub- 
stance (colloid). How does the colloid get there? Note the 
fibro-elastic stroma between the alveoli. Low power drawing. 
Under high power study and draw alveolus. What is the 
nature of the epithelium? Can you distinguish chief and 
colloid cells. Are any blood-vessels present in interalveolar 
stroma ? How can you distinguish thyroid from prostate 
gland? What, in a general way, is the function of the thy- 
roid? What morbid conditions are associated with atrophy 
and hypertrophy of thyroid? 
2. Parathyroid and thyroid of dog. 
At one end of the thyroid may be seen a small dark stain- 
ing area. This is a section of the parathyroid. Study with 
low and high power. Note the dense cords of cells, separated 
by stroma containing capillaries and small blood-vessels. 
Identify "principal" and "acidophilic" cells. Which are in the 
majority? Draw small portion under high power. Probable 
function of parathyroid? 
3. Human parathyroid. 
Study under high power and compare with preceding prep- 
aration. Often the gland appears as numerous epithelial 
masses separated widely by adipose and loose connective tissue. 
4. Thymus. 
This gland has been previously studied as a lymphoid organ 
and its structure should be briefly reviewed. What special 
features indicate its function as gland of internal secretion ? 
5. Adrenal gland (suprarenal gland). 
Under ocular and low power make out capsule, cortex, 
medulla and fine connective tissue trabeculae extending from 
capsule and forming framework of gland. In cortex note the 
glomerular, fascicular and reticular zones. The medulla is 
stained light in this specimen. Does it contain blood-vessels? 
Make topography drawing. 
103 MEMORANDA The Endocrin Glands. 
105 
High power. Study carefully structure and arrangement 
of cells in the three zones of the cortex. The cytoplasm of 
these cells is filled with many fat droplets which give to the 
cytoplasm a reticulated appearance. This is especially marked 
in the cells of the fascicular zone. Note the presence of 
brownish pigment granules in reticular zone. In medulla note 
irregular cords of oval or polyhedral cells which stain deeply 
with chromic acid salts. These are the "chromaffin" cells of 
the adrenal gland. What is their specific secretion? Study 
wall of central vein. • How does it differ from other veins 
studied? Draw strip including capsule, cortex and medulla, 
indicating structures studied in each. 
6. Adrenal of dog. 
Compare with man and note that medulla is separated from 
cortex by thin connective tissue capsule. Significance ? 
Note.-What is the probable function of the cortex? of 
the medulla? What evidence do we have that the human 
adrenal represents a fusion of two originally separate glands? 
What other "chromaffin" masses are found in the human 
body? What is their origin? What is peculiar about the 
blood supply of the adrenal gland ? 
7. Pineal gland (epiphysis). Longitudinal section. 
Under low power note body and stalk of gland, capsule 
and trabeculae giving the gland an incomplete lobation. Study 
gland with high power and note (a) epithelial ("secretory") 
cells, (&) neuroglia cells and fibers, (c) sinusoid capillaries. 
Reticular connective tissue may be present and mingle with 
the neuroglia fibers. How can you distinguish "secretory" 
from neuroglia cells? Do you find any melanic pigment gran- 
ules? Where? What is meant by brain sand? Is any found 
in your specimen? High power drawing of portion of gland. 
What function is ascribed to the epiphysis? From what 
structure is it derived ? What histological features distinguish 
the old from the young epiphysis? 
8. Pituitary gland (hypophysis). Sagittal section. 
With ocular and low power identify the posterior lobe 
(pars neuralis), the intermediate part (pars juxta-neuralis), 
anterior lobe (pars distalis). The cleft between the inter- 
mediate part and the anterior lobe is the lumen residuale. 
What is the derivation of each of the above parts? Study 
under high power and draw small area of (a) posterior lobe, 
noting the large amount of neuroglia cells and fibers, (&) in- 
termediate part. Note cuboidal cells arranged in form of 
alveoli, and sinusoidal capillaries. Is colloid present in alveoli ? MEMORANDA The Endocrin Glands. 
107 
(c) Anterior lobe. Note capsule and delicate trabeculae 
traversing lobe. Note central cords of cells (acidophilic and 
neutrophilic) surrounded by capillaries, and narrow peripheral 
zone of basophilic cells. What is meant by "chromophil" and 
"chromophobe" cells? Significance? What is the probable 
function of the pituitary gland? MEMORANDA CHAPTER XVI. 
NERVE TISSUE. 
A. The Neurone; The Neurone Body. 
1. Transverse' section of the lumbar enlargement of the 
spinal cord. Cajal's silver stain. (Neurone bodies and 
processes stained brown to black, neurofibrils stained 
black.) 
Low power. Note the pia surrounding the cord, the 
ventral longitudinal sulcus, dorsal septum and central canal 
(if present). Note blood-vessels in pia mater and cord. 
Within the cord note the dorsal and ventral gray columns 
or horns, surrounded by the white matter (here showing 
transversely cut axis-cylinders of nerve fibers), composing 
the white columns of the cord. In the ventral horn note 
the large motor cells, the present object of study. Select 
a motor cell which displays well its dendrites, nucleus and 
neuro-fibrils (not stained too darkly nor too pale). 
High power. Study and draw the body (perikaryon), 
dendrites and neuro-fibrils (forking at acute angles), nucleus 
and nucleolus (dark stained). Do the neuro-fibrils extend 
into the dendrites? What is their general arrangement? 
Do you think they anastomose ? Find, if possible, and draw 
a cell showing the axone (axis-cylinder process), distin- 
guishable by its tapering rather abruptly, on leaving the cell 
body, to a slender thread and then enlarging again to a 
uniform diameter. Can you distinguish neurofibrils within 
it? If you find an axone given off from a dendrite, notify 
one of the instructors. Note everywhere in the gray the 
cut-off pieces of axones and dendrites of various nerve cells. 
Do you think the neurofibrils may conduct the nerve im- 
pulses? Reasons? 
2. Transverse section of the lumbar enlargement of the 
spinal cord. Nissl's stain (nuclear chromatin and cyto- 
plasmic chromophilic substance of Nissl stained blue). 
Low power. Note the same features in general as in the 
preceding section. Under low power note especially the 
blood-vessels and the nuclei of neuroglia cells scattered 
throughout the section. Select a motor cell of the ventral 
horn which shows its nucleus. 
High power. Study and draw the body, dendrites, 
nucleus, nucleolus and chromophilic bodies, carefully in- 
109 MEMORANDA Nerve Tissue. 
111 
dicating the distribution, size, shape and arrangement of 
the latter. Is their arrangement around the nucleus differ- 
ent from that near the periphery? Are there any chromo- 
philic bodies in the dendrites? If so, what is their shape in 
the dendrites? Find one at the bifurcation of a dendrite. 
Are there any within the nucleus? Is there any pigment 
present? If so, draw it. Find, if possible, and draw a cell 
showing the axone hill, distinguishable by the complete 
absence of chromophilic bodies. Do you think the chromo- 
philic bodies conduct nerve impulses? Reason? Study the 
smaller nerve cells found in the gray. Do their nuclei differ 
from those of the ventral horn cells? How does their shape 
differ from the latter, also the size, shape and location and 
arrangement of their chromophilic bodies? Draw several 
of these cells, selecting cells that differ from each other. 
Study and draw some of the cells in the gelatinous sub- 
stance of Rolando (at the tip of the dorsal horn). These 
cells show very little cytoplasm in the Nissl stain (cyto- 
chrome cells, as distinguished from the preceding soma- 
tochrome cells) and their nuclei are not so easily distin- 
guishable from those of the neuroglia cells. 
3. Transverse'section of the thoracic spinal cord. Nissl's 
stain. 
Study and draw (high power) one or two of the cells of 
Clarke's column. Flow do they differ in shape and arrange-, 
ment of their chromophilic bodies from the cells of the 
ventral horn? Study and draw one or two cells in the 
lateral horn. How do they differ from the ventral horn cells? 
4. Demonstration. Transverse section of the spinal 
cord. Golgi's chrome-silver impregnation (isolated cells 
with their dendrites and axones, often to their finest term- 
inations, stained black. Granules and irregular masses of 
silver precipitate are usually present). 
Note the branching dendrites and the axone if present. 
5. Section of the cortex of the cerebellum. Cajal's silver 
stain. 
Note the cells of Purkinje with richly branching den- 
drites. The axone is often distinguishable. 
6. Demonstration. Section of the cortex of the cere- 
bellum. Golgi's chrome-silver impregnation. 
Note the fine dendritic branches beset with ''gemmules." 
7. Section'of the cortex of the cerebellum. Nissl's stain. 
Study and draw (high power) a cell of Purkinje, show- 
ing nucleus and chromophilic bodies. Draw several of the MEMORANDA Nerve Tissue. 
113 
cells of the nuclear layer (caryochrome cells). Can you 
distinguish any cytoplasm in the latter? 
8. Section of the cortex of the pallium (cerebral hemis- 
phere). Nissl's stain. 
Study and draw (high power) several pyramidal cells. 
How do they differ in shape and in the size, shape and 
arrangement of their chromophilic bodies from the cells 
of the ventral horn? 
9. Demonstration. Section of the cortex of the pallium. 
Golgi's chrome-silver impregnation. 
Note the shapes of the pyramidal cells, their long apical 
and shorter basal dendrites and their axones arising from 
the bases of the cells. Sometimes collateral branches from 
the axones can be seen. 
10. Transverse section of the cord. Marchi's osmic stain. 
Study and draw (high power), in the ventral horn cells, 
the pigment (lipochrom) stained black. Is it scattered 
throughout the cell or aggregated in one place? Is it a 
solid mass or composed of granules? 
11. Transverse section of the thoracic cord. Cajal's 
silver stain. 
Draw (high power) one or two cells of Clarke's column 
and also of the lateral horn. How does their shape differ 
from the ventral horn cells? 
12. Longitudinal section through a spinal ganglion. 
Cajal's silver stain. 
Low power. Note the general shape of the ganglion, its 
connective tissue capsule, the numerous bodies of spinal 
ganglion cells and the bundles of axones passing through 
it, mostly longitudinally but a number more transversely. 
High power. Draw one or two ganglion cells, selecting 
those showing the greatest length of process. Draw the 
nucleus and nucleolus and the neurofibrils when shown. If 
not shown draw them in a thinner slice cut off from a 
ganglion cell body. Note around the ganglion cell a 
wreath of brown nuclei, the nuclei of the capsule cells. 
What is the difference in connections of the longitudinal 
and transverse fibers? Try to find a bifurcating fiber. 
What is the significance of the bifurcation? 
13. Longitudinal section through a spinal ganglion. 
Nissl's stain. Also Weigert's iron haematoxylin and eosin. 
Low power. Note the connective tissue capsule (stained 
more pinkish in the haematoxylin-eosin stain), the numerous 
*8 MEMORANDA Nerve Tissue. 
115 
bodies of ganglion cells, nerve fibers and nuclei (of capsule, 
neurolemma, connective tissue and ganglion cells). Note 
blood-vessels. 
High power. Study and draw several of the ganglion 
cells, showing their nuclei, nucleoli and chromophilic 
bodies. How many types of cells can be distinguished ac- 
cording to the number, size and arrangement of their 
chromophilic bodies and the depth of the general staining 
of their bodies? Draw one of each type. Observe and 
draw the nuclei of the capsule cells enveloping each gang- 
lion cell. 
14. Longitudinal section through a vertebral sympa- 
thetic ganglion and the sympathetic cord. Ranson's pyridin 
modification of Cajal's silver stain. 
Low power. Note the ganglion containing many closely 
aggregated ganglion cell bodies and the longitudinally cut 
axones. The coarser lighter staining' processes are the 
dendrites of the ganglion cells. Fine, more deeply stained 
fibers between the ganglion cells are fibers from the spinal 
cord. 
High power. Find, if possible, a ganglion cell showing 
its dendrites and draw it. 
15. Demonstration. Section of nerve cells showing the 
canaliculi of Golgi-Holmgren. 
16. Demonstration. Section of nerve cells showing 
mitochondria. 
B. The Neurone; The Nerve Fiber. 
1. Transverse section through the sciatic nerve. Osmic 
stain. 
Low power. Note that the nerve fibers are arranged in 
definite bundles (fasciculi), each of which has a definite con- 
nective tissue covering, the perineurium. Connective tissue 
is also present within the fasciculi (endoneurium). Around 
the whole nerve is an investment of looser connective tissue 
which also passes within between the perineural coverings 
of the fasciculi (epineurium). Note the presence of blood- 
vessels in epineurium, perineurium and within the fasciculi. 
Study the nerve fibers composing the fasciculi: their myelin 
sheath, stained black, containing the unstained axis- 
cylinder or axone. Are the nerve fibers all the same size? 
Make a rough estimate as to how many are present in the 
whole nerve. Draw the whole nerve in outline, outlining MEMORANDA Nerve Tissue. 
117 
also each fasciculus and adding details in a small portion of 
one fasciculus. 
High power. Study and draw several nerve fibers. 
2. Longitudinal section through a nerve. Osmic stain. 
Low power. Note the nerve fibers only. Many of them 
may appear to be swollen and contracted along their course, 
blow do you interpret this? Find a fiber showing a node 
of Ranvier. 
High power. Draw a niedullated nerve fiber showing a 
node of Ranvier. Why are medullated fibers sometimes 
called double contoured fibers? Upon what optical effect 
does the phenomenon depend? At the node of Ranvier 
note, if possible, the axis-cylinder and neurolemma sheath 
passing across the node. Find and draw a fiber showing the 
clefts of Schmidt-Lantermann. These divide the myelin 
sheath into funnel-shaped segments. Do they all extend in 
the same direction in the same fiber? Are they always the 
same distance apart? What is possibly their real nature? 
The nuclei of the neurolemma cells may sometimes be seen 
but are more evident in sections stained with nuclear stains. 
3. Teased, unstained piece of fresh nerve. 
A piece of fresh nerve, kept in normal salt solution, 
should be carefully teased apart with two needles until a 
few fibers at least are well isolated and then a cover slip 
placed over it. 
Low power. With the diaphragm of the microscope 
carefully adjusted, look for single nerve fibers which have 
not been injured and observe the same points as in No. 2. 
What is the principal difference in appearance between the 
fresh and osmic stained fiber, and to what is it due? The 
clefts of Schmidt-Lantermann are very well seen in the 
fresh nerve. 
4. Transverse section of a nerve. Mallory's phospho- 
tungstic haematoxylin stain. 
Low power. Note the same general structures noted 
in 1. 
High power. Carefully study and draw several indi- 
vidual nerve fibers. Here the axis-cylinder is stained red 
and the myelin yellowish. The connective tissue is stained 
blue. Note the radiating lines passing through the myelin 
sheath. They belong to the "neurokeratin" network. Oc- 
casionally the myelin sheath appears to be divided into two 
concentric rings. To what is this appearance probably due? 
5. Longitudinal section of a nerve. Mallory's phospho- 
tungstic haematoxylin stain. MEMORANDA Nerve Tissue. 
119 
Repeat the observations made on previous longitudinal 
sections of nerve. 
6. Longitudinal section of a nerve fixed in alcohol and 
stained with haematoxylin and eosin. 
Low power. Note that the nerve-fibers have a granular 
appearance. The axis-cylinder is usually indistinct. All 
nuclei are clearly shown. 
High power. Study and draw one or two nerve fibers, 
showing the neurokeratin network and neurolemma nuclei. 
While some of the nuclei present are connective tissue 
nuclei (endoneurium, etc.), those closely applied to the 
outer side of the myelin sheath may be regarded as neuro- 
lemma nuclei. Some of these nuclei appear to be thin, 
deeply staining! nuclei, while others appear to be oval and 
not so deeply stained. To what is this difference in ap- 
pearance due? 
7. Transverse section of a nerve. Mallory's orange- 
anilin blue fuchsin stain (axis-cylinder red, myelin orange, 
connective tissue blue). 
High power. Repeat the observations made upon the 
previous transverse sections of nerve. 
8. Longitudinal section of a nerve. Mallory's orange- 
anilin blue fuchsin stain. This stain demonstrates the 
neurokeratin network, axis-cylinder and nodes of Ranvier 
very well. 
High power. Repeat the observations and drawings 
made upon previous longitudinal sections of nerve. 
9. Transverse section of a spinal cord. Weigert's myelin 
stain (stains medullary or myelin sheath blue). 
Low power. Note the transversely cut, longitudinal 
nerve fibers in the white matter and the longitudinally cut 
nerve fibers in the gray matter. Note also the nerve fibers 
in the roots just outside the cord. 
High power. Draw several nerve fibers in the white 
matter. What previous preparation do they resemble? 
10. Transverse section of a spinal cord. Cajal's silver 
stain. 
Repeat the observations made on section 9. What are 
the differences in appearance between the nerve fibers here 
and in 9? To what are they due? In the gray the frag- 
ments of axis-cylinders cannot always be distinguished from 
the fragments of dendrites. MEMORANDA Nerve Tissue. 
121 
11. Transverse section of a spinal cord. Hsematoxylin- 
eosin or Mallory's phosphotungstic hsematoxylin. 
Repeat the observations made on sections 9 and 10. 
12. Longitudinal section of a spinal cord. Cajal's silver 
stain. 
Low power. Note the longitudinally cut fibers of the 
white matter of the cord. 
High power. Draw several of the above. 
C. Secondary Degeneration of Nerve Fibers. 
1. Longitudinal section of the distal stump of a nerve 
3 to 5 days after cutting. Osmic stain (staining both 
normal and degenerating myelin black). 
Low power. Note the fragmentation of the myelin 
sheaths into a series of elongated segments with rounded 
ends and often completely disconnected. Compare with 
normal nerve. 
High power. Draw portions of several fibers showing 
the above. Are the segments of degenerating myelin 
larger than the normal nerve fibers, i.e., are they swollen? 
2. Longitudinal section of the distal stump of a nerve 
3 to 5 days after cutting. Marchi's stain (staining black only 
the degenerating myelin and the fatty products of the 
neurolemma cells). 
Low power. Note that the nene (lightly stained) 
shows the same changes as in the preceding section but 
that there are also a number of rather coarse black granules, 
not present in the normal nerve stained with Marchi's stain. 
3. Longitudinal section of the distal stump of a nerve 
12 to 15 days after cutting., Osmic stain. 
Low power. Note that the larger part of the nerve is 
now stained pale, owing to the disappearance of much of 
the myelin sheaths. What is left of the degenerating mye- 
lin is groups of black granules of various sizes with here 
and there an elongated fragment of the former myelin 
sheath. If the nerve was only partly cut many normal 
myelin sheaths belonging to the uncut fibers may be seen. 
The much larger fat cells, stained black, may be seen in 
the sheaths of the nerve. ' 
High power. Carefully study the above groups of gran- 
ules. They will appear to be contained in vesicles which 
are within fibers (band fibers, pale in the osmic stain) which 
are much thinner between the groups of granules. Note 
that the granules may be stained with various degrees of MEMORANDA Nerve Tissue. 
123 
intensity. How do you interpret this and also the fact that 
the granules are of various sizes? Draw portions of one 
or more band fibers, showing several groups of granules. 
4. Longitudinal section of the distal stump of a nerve 
12 to 15 days after cutting. Marchi's stain, haematoxylin and 
eosin. 
Low power. Note that the granules appear much the 
same, but, in addition, nuclei, connective tissue and band 
fibers are better stained. Fat cells (black) may be present. 
High power. Study and draw several band fibers and 
their included groups of granules as above. Observe also 
the thin or oval nuclei, most of which belong to the band 
fibers. What is the origin of these band fibers and their 
nuclei? What physiological relation might you infer the 
band fiber bears to the granules? What may be its func- 
tion? 
5. Longitudinal section of the distal stump of a nerve 
12 to 15 days after cutting. Osmic and Weigert's iron 
haematoxylin stain. 
Low power. Note the same features as in section 3. If 
the nerve has been only partly cut many normal medullated 
fibers may also be seen. The haematoxylin stain will usu- 
ally bring out the band fibers and their nuclei more dis- 
tinctly (in blue or brown). 
High power. Draw portions of several band fibers and 
their enclosed groups of granules if the preparation shows 
points not clearly demonstrated by the preceding sections. 
D. Changes in the Neurone Body Produced by Injury to its 
Axone ("axonal" degeneration) or secondary degen- 
erative changes in Neurone Body. 
1. Transverse section of the medulla of a rabbit in which 
one of the hypoglossal nerves had been pulled out 3 to 5 
days previously. Nissl's stain. 
Low power. Locate the cavity lying near the dorsal 
aspect of the medulla and known as the fourth ventricle. 
Dorso-laterally to this on each side is a compact group of 
nerve cells, the dorsal motor "nucleus" (i.e., group of neu- 
rone bodies) of the vagus. Ventrally to this and ventro- 
laterally to the fourth ventricle is another larger group of 
larger and more scattered nerve cells. This is the hypo- 
glossal nucleus, the axones of which form the hypoglossal 
nerve. Note that while the cells of one hypoglossal nucleus 
present Nissl chromophilic bodies of normal appearance, MEMORANDA Nerve Tissue. 
125 
those of the other nucleus appear pale and the cell bodies 
more rounded. Select one of these cells showing also an 
eccentric nucleus. 
High power. Study the above cell, noting that it is 
swollen, that its nucleus is eccentric and that the chromo- 
philic bodies have disappeared from the interior of the cell 
leaving only a peripheral rim of these bodies (central 
chromatolysis). The nucleus does not show so much 
change but may appear paler than normal. Draw this and 
other cells showing variations. Some of the cells of the 
nucleus showing degenerative changes contain nuclei ap- 
parently centrally placed. How do you account for this? 
How can secondary degeneration be used in the study 
of the architecture of the nervous system? What does it 
tend to show as to the relations between neurones? What 
does it show as to the relation between neurone body and 
axone ? 
2. Transverse section of the medulla of a rabbit in which 
one of the hypoglossal nerves had been evulsed 12 to 15 
days previously. Nissl's stain. 
Low power. Make the same observations as on the 
previous section. Note that the cells and their nuclei, in 
the abnormal nucleus, are still paler and appearances in- 
dicate that some of them may have disappeared, the injury 
having been too severe to allow recuperation (regeneration) 
of the neurone. Why should the neurone be more severely 
affected in this case than in other cases of cutting or injury 
to its axone? 
How can "axonal" degeneration be used in the study of 
the architecture of the nervous system? What does it 
show as to the relation between neurone body and axone? 
3. Transverse section of the lumbar enlargement of a 
human spinal cord, the cauda equina of which had been 
previously crushed (thereby crushing the nerve roots below 
the end of the cord). Nissl's stain. 
Low power. Note the presence in the ventral horn of 
swollen, pale motor cells. 
' High power. In one or more of these cells study the' 
changes mentioned in section 1. Are there present any 
normal motor cells? If so, how do you account for their 
presence? MEMORANDA Nerve Tissue. 
127 
E. Changes in the Neurone Body Produced by Influences 
Acting Directly upon it ("primary" degenerative 
change). 
_ 1. Transverse section of the spinal cord of a case of 
rabies. Nissl's stain. 
Low power and high power. Study the motor cells of 
the ventral horn. Note that the swelling and eccentricity 
of nucleus are not as marked as in the "axonal" degenera- 
tion and especially note that there is a diffuse chromatolysis, 
i.e. not confined to any one part of the cytoplasm. Note 
also that there is a tendency to a general diffuse staining 
in addition to the disappearance of the chromophilic bodies. 
F. Regeneration of Nerve Fibers. 
1. Demonstration. Longitudinal section or sections of 
the distal stump of a nerve cut 15 days previously. Cajal's 
silver stain. In this section the fatty products of degen- 
erating myelin have been dissolved out in fixation, but in 
the spaces formerly containing them can be seen the black- 
stained granular remnants of the axis-cylinder. Note also 
the band fibers and their nuclei (brown). 
In some parts of the nerve there can also be seen thin 
black nerve fibers principally within the band fibers. These 
are the new nerve fibers which have grown into the distal 
from the central stump. 
2. Demonstration. Longitudinal section or sections 
through the central stump and scar of a nerve cut 15 days 
previously. Cajal's silver stain. 
Centrally along the central stump, normal axis-cylinders 
can be seen. As the scar is approached these are blacker 
and more slender (new outgrowths), in the scar these fibers 
take various directions according to the arrangement of the 
elements of the scar tissue and can also be seen wandering 
off in the adjacent connective tissue. Some of the growing 
nerve fibers terminate in large bulbs, others terminate in 
elongated structures containing spirally wound fibers, the 
spirals of Perroncito. 
G. Effect of Injury of Motor Neurones upon the Striated 
Voluntary Muscle Innervated by them. 
1. Longitudinal section of voluntary striated muscle in 
which the motor fibers have been destroyed (anterior polio- 
myelitis.) Marchi's stain, haematoxylin and eosin. MEMORANDA Nerve Tissue. 
129 
Note the numerous muscle fibers, reduced in size but 
still showing cross-striations (atrophy). Note also other 
much swollen fibers in which the myofibrils are very dis- 
tinct but the cross-striations are not visible. Some of these 
contain fine black granules (osmic blackened fat). These 
latter fibers show degenerative changes. Note also the 
large amount of fat present in the muscle sheaths. 
H. Peripheral Terminations of Nerve Fibers. 
1. Vertical section through the tip of the finger. Haema- 
toxylin and eosin stain. 
Low power. Look over the subepidermal papillae until 
one is found containing an elongated compact body with 
transverse nuclei-the tactile corpuscle of Meissner. 
High power. Study and draw one of the tactile cor- 
puscles. Note the transverse striations and nuclei indi- 
cating the presence of rather flattened epithelial-like cells, 
between which are the nerve terminations (not visible in 
this preparation). Note the connective tissue capsule sur- 
rounding the corpuscle. 
Low power. In the deeper layers of the derma look for 
large bodies consisting of concentric lamellae and presenting 
an onion-like appearance-the corpuscles of Pacini. 
High power. Note in one of the corpuscles (preferably 
one cut transversely) the regular connective tissue lamellae 
surrounding a homogeneous core which contains the term- 
ination of a nerve fiber (not visible in this preparation). 
About how many lamellae are there? In some corpuscles 
an outer and inner portion of the whole lamellar coat may 
be distinguishable. What is the probable function of this 
thick covering to the enclosed nerve ending? Of what part 
of the nerve is it a continuation? 
2. Vertical section of a finger tip. Cajal's silver stain. 
Low power. Look over each papilla until one is found 
which contains fine brown or black fibers (barely visible 
with low power). If the fibers cannot be distinguished with 
low power, examine each one with high power until a 
papilla containing nerve terminations is found. In this 
preparation the only portion of the tactile corpuscles clearly 
visible are the nerve endings within it. Note the nerve fiber 
or fibers proceeding upward and entering the tactile cor- 
puscle after which it divides into several branches which 
pass around forming a spiral or whorl within the corpuscle. 
Draw one or more of the corpuscles showing their nerve 
terminations. 
9 MEMORANDA Nerve Tissue. 
131 
If there are any corpuscles of Pacini present, note the 
points observed in section 1, and also the brown-stained 
nerve fibers in their cores. 
3. Demonstration. Section showing intraepithelial nerve 
terminations. Golgi's chrome-silver impregnation. 
Note the black stained nerve fibers passing between the 
epithelial cells (outlines not visible) and terminating near 
the surface. 
4. Demonstration. Section showing termination of a 
motor nerve in a motor end plate in striated voluntary 
muscle. 
5. Demonstration. Section through the heart of an 
amphibian. Golgi's chome-silver impregnation. 
Note the delicate black nerve fibers, with varicosities, 
passing among the muscles.' Owing to their simple un- 
branched character, the exact mode of termination is not 
easily determined. 
6. Demonstration. Section through the gut of an 
amphibian. Golgi's chrome-silver impregnation. 
Note the black nerve fibers passing among the smooth 
muscle of the wall of the gut and apparently terminating 
in small bulbs. 
I. The Neuroglia and General Structure of the White and 
Gray Matter, including the Mesodermal Elements. 
The Meninges. 
1. Demonstration. Transverse or longitudinal section 
of the spinal cord. Golgi's chrome-silver impregnation. 
Note the two types of neuroglia (or glia) cells; those 
with irregular, shorter, rough processes, in which probably 
the cytoplasm of large glia cells is stained, and smaller cells 
with long thin, often straight, unbranched processes. The 
latter are especially seen in the white matter and in them 
the glia cell body and glia fibers in connection with the cell 
body are stained. In this or other preparations glia cells 
attached by their processes to walls of blood-vessels may be 
seen. 
2. Demonstration. Section of the spinal cord (either 
normal or multiple sclerosis). Weigert's neuroglia stain 
(staining glia fibers blue). 
Note the glia cell nucleus surrounded by pinkish or 
yellowish, vaguely outlined glia cytoplasm. The glia fibers 
(blue) tend to form the boundary of the cell and pass off 
in its processes. MEMORANDA Nerve Tissue. 
133 
3. Transverse section of the spinal cord. Mallory's 
phosphotungstic haematoxylin stain (Zenker fixation). 
Study the structure of the ependyma, surrounding the 
central canal. The ependymal cells resemble, in such stains, 
columnar epithelial cells. 
Low power and high power. In the outermost part of 
the cord a thin zone can be seen, immediately beneath the 
pia and destitute of nerve fibers. This is the marginal glia 
Note a thin blue line forming its outer boundary, the ex- 
ternal limiting glia membrane Immediately beneath can 
be seen a number of small branched cells, marginal glia 
cells. Throughout the white matter and gray can be seen 
the nuclei of glia cells. 
Note also the blood-vessels (red blood corpuscles deep 
blue). Their structure is the same as elsewhere. Can any 
connective tissue be distinguished around the endothelium 
of the capillaries in the cord? Note the pia mater and its 
structure (better in following sections). 
Make high power drawings of ependyma, marginal glia 
and adjacent pia and white matter and drawings of blood- 
vessels within the cord. 
4. Transverse section of spinal cord Mallory's phospho- 
tungstic haematoxylin (fixation in Orth's fluid). 
Repeat the observations made in section 3. The central 
canal may be obliterated. Note the clump of glia cells 
representing its former location. There may be also smaller 
nests of glia cells in the central gelatinous substance in the 
vicinity. 
Note especially the marginal glia and the glia septa 
passing inward among the transversely cut nerve fibers. 
Now and then individual (blue) glia fibers can be distin- 
guished. How do the nerve fibers of the white matter 
appear? 
Note the structure of the pia and its blood-vessels. 
Note the entrance of blood-vessels into the cord from the 
pia. 
Make high power drawing of the pia, marginal glia and 
white matter, also of a blood-vessel. Enumerate the meso- 
dermal histological elements found within the spinal cord 
(and central nervous system in general). 
5. Transverse section of the spinal cord. Marchi's stain 
and safranin. 
Study (high power) the ependyma cells and note the 
numerous glia fibers in the central gelatinous substance. MEMORANDA Nerve Tissue. 
135 
6. Transverse section of the spinal cord (infant). Nissl's 
stain. 
Note the deeply stained nuclei of the ependyma cells. 
Throughout the gray and white matter note the numerous 
glia nuclei. In certain portions of the gray, especially the 
gelatinous substance of Rolando, it may be difficult to dis- 
tinguish between the neuroglia nuclei and the nuclei of cer- 
tain small (cytochrome) nerve cells; in the white matter, 
however, there are no nerve cells to cause this confusion. 
Small portions of gray and white should be drawn (high 
power) showing the glia nuclei. 
Study and draw (high power) also, portions of some of 
the larger blood-vessels and capillaries of the cord. Enu- 
merate the various histological elements in the cord to which 
the various nuclei belong. Draw a small portion of the pia. 
7. Transverse section of the spinal cord. Cajal's silver 
stain. 
Note the marginal glia. Study and make high power 
drawing of a small portion of the gray matter showing cells, 
nuclei, fragments of dendrites and axones. High power 
drawing of a small part of the white matter. The glia 
nuclei are not deeply stained but can usually be distin- 
guished. 
8. Transverse section of the spinal cord. Weigert's 
myelin stain. 
Repeat the observations and drawings made on section 7. 
9. Vertical section of the cerebral cortex with pia- 
arachnoid attached. 
Low power and high power. Study and draw a small 
portion, showing its loose connective tissue and blood- 
vessels. 
10. Transverse section of the dura mater. Haematoxylin 
and eosin stain. 
Draw the dense white connective tissue of which it is 
composed. Is it as vascular as the pia? Why? MEMORANDA CHAPTER XVII. 
THE NERVOUS SYSTEM. 
A. The General Arrangement of the Peripheral Nervous 
System. 
1. Transverse section of the body of a 14 mm. pig em- 
bryo. Haematoxylin and eosin stain. 
Low power. Note the gut and its appendages, coelom, 
body wall, spinal cord, vertebral column (notochord), 
mesentery and aorta. 
Note the spinal ganglia connected with the cord and with 
the ventral root by dorsal root fibers and the ventral root 
fibers emerging, often in several bundles, from the ventral 
part of the cord. Note the junction of dorsal and ventral 
roots to form the spinal nerve. Beyond this is given off the 
dorsal branch or division to the medial dorsal part of the 
trunk. Still further peripherally is given off a branch which 
passes, latero-ventral to the vertebral canal, towards the 
mesentery. This is the white (and gray) ramus communi- 
cans. Ventro-lateral to the vertebral column scattered cells 
stained somewhat more darkly can often be seen. They 
are the vertebral sympathetic ganglia. The nerve cannot 
usually be traced further, but in the mesentery it passes into 
the prevertebral ganglia. Draw an outline of the dorsal 
part of the body down to the gut, and carefully indicate and 
label the various structures enumerated above. Most of the 
connections will be present on either one side or the other. 
2. Transverse section or sections of a chick embryo of 
the 6th or 7th day of incubation. Golgi's chrome-silver im- 
pregnation. 
Low power. Repeat the observations made in the pre- 
ceding section. The young nerve fibers are stained black. 
There are present also many granules and masses of silver 
precipitate of no significance. 
In the chick the vertebral sympathetic ganglion is 
closely adjacent to the ventral root at about the point of its 
junction with the dorsal root. Some fibers may be seen 
entering it. In one of the sections a few of the embryonic 
bipolar spinal ganglion cells are stained. Trace the central 
process into the cord and the peripheral process as far into 
the spinal nerve as possible. Occasionally the embryonic 
nerve fibers can be seen in the sympathetic plexuses in the 
wall of the gut. What are the ultimate destinations of the 
137 MEMORANDA The Nervous System. 
139 
peripheral processes of the spinal ganglion cells? Of the 
fibers of the white rami communicantes ? Of the rest of 
the ventral root fibers? Of the axones of the vertebral sym- 
pathetic ganglion cells? Of the axones of the prevertebral 
(not seen in the preparation) sympathetic ganglion cells? 
What are the gray rami communicantes? Why "gray"? 
3. Longitudinal section of a vertebral sympathetic 
ganglion and the sympathetic cord (previously studied). 
Ranson's modification of Cajal's silver stain. 
Low power. Note especially the longitudinally cut 
axones (mostly medullated but the myelin not present or 
stained) of the sympathetic cord, entering or passing by 
the vertebral ganglion. What are the destinations of these 
fibers? 
B. Spinal Cord: Histogenesis and General or Fundamental 
Arrangement of its Nervous Elements. 
1. Transverse section of the body of a 14 mm. pig em- 
bryo (previously studied). Haematoxylin and eosin stain. 
Low power. Locate the spinal cord and note its shape, 
central canal, the black stained nuclei (chromosomes) of 
certain cells next to the central canal, the radially arranged 
nuclei of the nuclear layer, the mantle layer' (in the ventro- 
lateral portion of the cord external to the nuclear layer) 
with more rounded and loosely arranged nuclei and, next 
to the periphery, the thin marginal layer, destitute of 
nuclei. Note the dorsal roots entering the marginal layer 
of the dorso-lateral part of the cord. What is their origin? 
Note the ventral root fibers passing, usually in several fasci- 
culi, from the ventro-lateral mantle layer, through the mar- 
ginal layer and then leaving the cord. What is their ulti- 
mate destination? Note the transversely cut fibers in the 
marginal layer just ventral to the entering dorsal root fibers 
and in the ventro-lateral marginal layer. Note also the 
fibers passing transversely around the cord between the 
nuclear and mantle layers (internal arcuate fibers) and 
crossing to the other side ventral to the central canal (ven- 
tral commissure of the cord). (For their origin and des- 
tination see following sections). Is the cell proliferation 
confined to one locality? What is the natural consequence 
as to the further location and differentiation of the daughter 
cells? Is differentiation further advanced in the dorsal or 
ventral part of the cord? Evidence? How do you account 
for the different appearance of the mantle layer? What is MEMORANDA The Nervous System. 
141 
the ultimate fate of the nuclear layer? Of the mantle layer? 
Of the marginal layer? 
Make (low power) a rather large outline of the whole 
cord and its central canal, faintly indicate the boundaries 
of the above layers and fill in (using low power and high 
power) the details (arrangement of nuclei and fibers) in a 
portion at least of one side. 
2. Demonstration. Longitudinal horizontal section of 
the body of a chick embryo of 6 or 7 days incubation, pass- 
ing through the dorsal part of the spinal cord. Golgi's 
chrome-silver impregnation. 
Low power. Locate the cord and note the dorsal root 
fibers entering from the sides and undergoing in the cord 
Y-shaped divisions into longitudinal ascending and de- 
scending arms. Usually either from the main dorsal root 
fiber or from its arms right angled branches (collateral 
branches) are seen. (See also section 4). Draw the out- 
line of the cord and carefully draw the bifurcations of 
several of the dorsal root fibers. Disregard silver precipi- 
tates (see next section). 
3. Transverse section of the body of a chick embryo of 
6 or 7 days incubation. Golgi's chrome-silver impregnation. 
Low power. Note that in all parts of the preparation 
there are black granules and irregular black masses. These 
are silver precipitates and should be ignored. In the cord 
there is also often a coarse, anastomosing, brown meshwork. 
These are capillaries and are not to be confused with the 
much finer, black, non-anastomosing nerve fibers. Locate 
the cord and note its shape and central canal. Distinguish 
also between the nuclear and mantle layers (future gray 
matter of the cord) and the marginal layers (future white 
matter). The latter is usually somewhat lighter in color 
and often contains a number of black stained axones cut 
transversely or obliquely. In the former layers try to find 
(low power and high power) one or more embryonic neu- 
rones whose axones can be traced to the marginal layer. 
The dendrites can usually be distinguished from the axones 
by their coarser, rougher, tapering appearance and irregular 
branching, whereas the axones are uniformly thin and usu- 
ally smooth in outline. If the axone passes to the marginal 
layer on the same side it is a tautomeric column cell, if to 
the marginal layer of the opposite side it is a heteromeric 
column cell. Occasionally one may be seen in which the 
axone splits, one division going to the same and the other 
to the opposite side (hecateromeric column cell). The turn- MEMORANDA The Nervous System. 
143 
ing and splitting of the above axones into the longitudinal 
fibers in the marginal layer cannot usually be seen in 
transverse sections. What are the possible ultimate des- 
tinations of the axones of the column cells? In the section 
there are also often to be seen cells extending transversely 
from central canal to periphery, of rough appearance and 
branching especially in the marginal layer. These are 
spongioblasts (embryonic glia cells). 
Draw a fairly large outline of the cord and its central 
canal and indicate faintly the boundary of the marginal 
layer. In this outline draw accurately (low power and high 
power) the column cells whose axones have been traced to 
or near the marginal layer and some of the spongioblasts. 
4. Transverse section of the body of a chick embryo of 
6 or 7 days incubation. Golgi's chrome-silver impregnation. 
Low power. Locate the cord and note its layers and 
central canal as in section 3. Note that from various parts 
of the marginal layer delicate transverse nerve fibers enter 
the nuclear and mantle layers and terminate there in ar- 
borizations. Sometimes it can be seen that these fibers are 
collateral branches ("collaterals") of the coarser longitud- 
inal (transversely cut) fibers lying in the marginal layer. 
Note that some of them come from the fibers in the dorsal 
part of the marginal layer (future dorsal white column of 
the cord) where the dorsal root fibers enter, i.e., from the 
ascending and descending arms of the dorsal root fibers. 
(See also section 2). Others come from the lateral and 
ventral parts of the marginal layer (from the future lateral 
and ventral white columns of the cord). Origin of these 
fibers? In some preparations collaterals from the dorsal 
root fibers may be seen passing all the way to the ventral 
(future) gray matter. Some of the fibers passing in from 
the marginal layer are terminations of the main fibers 
('"terminals"), not collateral branches. 
5. Longitudinal, horizontal section of the body of a chick 
embryo of 6 or 7 days incubation, passing through the 
spinal cord. Golgi's chrome-silver impregnation. 
Low power. Locate the cord and note the bands of 
longitudinally cut axones (black). These are the longi- 
tudinal fibers in the marginal layer or future white columns 
of the cord. The number of bands depends upon the plane 
and direction of the section (compare with previous trans- 
verse sections). 
From among the longitudinal fibers finer transverse 
fibers can be seen entering the (future) gray matter. These MEMORANDA The Nervous System. 
145 
are the collaterals studied in the previous section. Find 
(low power and high power) some longitudinal fibers which 
show the T-shaped branching of one of its collateral 
branches, thereby demonstrating the exact origin of many 
of the transverse fibers. Other transverse fibers are ob- 
viously the axones of the column cells passing to the white 
matter and then by bending or splitting forming a longi- 
tudinal column fiber, or a longitudinal column fiber turn- 
ing into the gray to terminate ('Terminals") there. It may 
not always be possible to observe these latter points. The 
student should now be able to construct from the neurones 
studied the following reflex spinal arcs or circuits: (a) An 
uncrossed arc, involving two neurones, from a receptor to 
striated voluntary muscle, (b) An uncrossed or crossed 
arc, involving three neurones, from a receptor to voluntary 
striated muscle, (c) An uncrossed or crossed arc, involving 
four neurones, from a receptor to a smooth muscle or gland. 
C. Spinal Cord: General Topography and Arrangement of 
Fibers. 
1. Transverse section of the lumbo-sacral spinal cord 
of a 7 months human foetus. Weigert's myelin stain. 
Note the dorsal and ventral gray horns and the few 
transverse medullated fibers passing between the white 
columns and the gray. What are the probable origins and 
destinations of these fibers? (Compare with B. 4). 
2. Transverse section of the lumbo-sacral (infant's) 
spinal cord. Weigert's myelin stain. 
Naked eye, ocular and low power. Note the general 
shape of the cord, its central canal (open in the young 
cord), the ventral longitudinal sulcus, the dorsal medial 
septum and the enveloping pia mater. Note the dorsal and 
ventral gray columns or horns (stained lighter than the 
white matter. Why?). In the dorsal gray horn note a 
somewhat narrower basal part (cervix or neck) expanding 
dorsally into the caput or head. Capping the latter is a 
very light area (few medullated fibers) of a homogeneous 
appearance, the gelatinous substance of Rolando, properly a 
part of the dorsal horn. In the infant, the light area in- 
dicating the presence of the gray horn apparently extends 
to the periphery. When examined more closely it is seen 
to be composed of a lighter portion next to the gelatinous 
substance and containing a plexus of fibers. This belongs 
to the gray and is the zona spongiosa. External to this, 
between it and the periphery of the cord is an area oc- 
10 MEMORANDA The Nervous System. 
147 
cupied by fine transversely cut nerve fibers. This is the 
terminal (dorso-lateral) zone of Lissauer and is properly 
the lateral, fine-fibered portion of the dorsal white column 
of the cord. Note the large ventral gray horn with pro- 
trusions due to the presence within it of groups of large 
motor cells. The portion of the gray connecting the dorsal 
and ventral horns is the intermediate gray. Note the com- 
missures connecting the two halves of the cord. Note, ven- 
trally to the central canal, a conspicuous bundle of fibers 
crossing from one side to the other, the ventral or anterior 
white commissure of the cord. Between it and the central 
canal is some gray matter, the ventral gray commissure. 
Dorsal to the canal is more gray matter (dorsal gray com- 
missure) and, further dorsal, a comparatively few, crossing 
fibers (dorsal white commissure). The light, homogeneous 
area around the central canal is the central gelatinous sub- 
stance. It is in reality different from the gelatinous sub- 
stance of Rolando^ consisting largely of neuroglia while the 
gelatinous substance of Rolando is largely composed of 
small nerve cells (see section D. 1). 
Note outside the gray matter of the cord, the darkly 
stained white matter. One light area in the lateral portion 
of the white matter in the infant, is the as yet non-myelin- 
ated or incompletely myelinated lateral pyramidal tract. 
Distinguish the dorsal, or posterior, white column (or funi- 
culus) comprising that portion of the white matter from 
dorsal septum to and including the zone of Lissauer, the 
lateral white column extending from the zone of Lissauer 
and merging, at about the exit of the ventral root fibers, 
into the ventral white column comprising the rest of the 
white matter. 
Draw, using naked eye and ocular, a full page outline 
of the whole (or at least more than one-half) of the cord 
and central canal, and indicate by faint lines the outlines 
of the gray matter and the gelatinous substance of Rolando. 
Study and draw, in one field (low power) at a time, the 
details of the arrangement of the nerve fibers. Study the 
entrance and distribution of the dorsal root fibers. Note 
that on entering, fine fibers pass laterally from the root 
and enter the zone of Lissauer (fine-fibered portion of dorsal 
root). Note that the remaining, coarse fibers (coarse- 
fibered medial portion of dorsal root) usually pass through 
the zone of Lissauer, dividing it into larger lateral and 
smaller medial portions. They then can be seen to pass 
medially along the dorsal and mesial side of the gelatinous 
substance of Rolando. This is the zone of entry and MEMORANDA The Nervous System. 
149 
radiation of the dorsal roots (obviously applicable only to 
the coarse fibers) and is the area in which their fibers split 
into ascending and descending arms. Some of the coarse 
root fibers, in some levels, appear to pass through the 
medial part of the gelatinous substance of Rolando and into 
the caput of the dorsal horn before dividing. 
From the zone of entry and also from the dorsal white 
column medial to this, bundles of fibers can be seen passing 
into the gray. Some of these bundles pass through the 
gelatinosa and some sweep around medial to it (some of 
the latter fibers probably end in the gelatinosa). Note that 
the fibers composing these bundles are finer tlfan the root 
fibers and the longitudinal fibers of the dorsal column, 
thereby indicating that they are collaterals. Note that 
many of these bundles can be traced into the intermediate 
gray and occasionally even further ventrally. What would 
be the probable significance of those traceable into the 
ventral horn? Other fibers from the zone of entry which 
either pass medially to or through the gelatinosa form a 
plexus in the caput of the dorsal horn, and still others pass 
laterally and curve dorsally into the gelatinosa. (Other 
collaterals from the zone of Lissauer also contribute to this 
plexus and others terminate in the zone of Lissauer, but 
many of these are not visible in Weigert preparations, being 
non-medullated.) Study the fine fibers of the dorsal white 
commissure. Some of these are collaterals from the dorsal 
white column, others are lost in the gray (ultimately col- 
laterals from the lateral columns and some axones of cells 
in the gray). Study the transverse fibers passing between 
the dorsal part of the lateral columns and the gray, in part 
collaterals, in part terminals, in part fibers to the white 
matter. Note that in the ventral horn two sizes of fibers 
are very apparent. A comparatively few are very coarse 
and are obviously the myelinated axones of the large motor 
cells of the ventral horn (ventral root fibers). Besides 
these note the great number of finer fibers entering the 
gray from the white columns on all sides. Larger numbers 
separate the groups of motor cells, a smaller number pass 
between the individual motor cells. Many of these also are 
collaterals. Study the fibers of the ventral white commis- 
sure. The bulk of these are coarse fibers, many of them 
connecting the gray of one side with the opposite ventral 
white column. What is the origin of most of these fibers? 
Note that there are also fine fibers, in part probably 
collaterals. Carefully label all parts shown in the drawing. MEMORANDA The Nervous System. 
151 
3. Transverse section of the lumbo-sacral adult spinal 
cord. Weigert's myelin stain. 
Naked eye, ocular and low power. Observe the points 
named in section 1. Note that the number of medullated 
fibers in white and gray has much increased and that the 
plexuses in the latter cannot be analyzed so readily. Note 
the great increase in fine medullated fibers in the zone of 
Lissauer. 
4. Transverse section of the lumbo-sacral (infant's) 
spinal cord. Cajal's silver stain. 
Low power. Study the arrangement of the fibers noting 
the same points as in section 1. 
5. Transverse section of the lower thoracic (infant's) 
spinal cord. Weigert's myelin stain. 
Low power. Note the points covered in section 1. 
Study in this especially the fibers related to Clarke's column. 
Note that from the middle of the dorsal white column 
bundles of fine fibers, evidently collaterals, enter and form a 
plexus within Clarke's column. Note also that from the 
ventral side of Clarke's column coarse, heavily myelinated 
fibers issue and pass laterally across the gray and into the 
lateral white column to a point near the periphery where 
coarse fibers can be seen cut transversely. Interpret these 
appearances. What are the relations of the fine and coarse 
fibers respectively to Clarke's column? 
6. Transverse section of the lower thoracic adult spinal 
cord. Weigert's myelin stain. 
Low power. Note the same points as in section 5 and 
the increase in medullated fibers as noted in section 3. 
7. Transverse sections of the lower thoracic adult and 
infant's spinal cords. Cajal's silver stain. 
Low power. Note the points mentioned in section 5 
concerning Clarke's column and fibers in relation with it. 
Note especially the fibers from the dorsal white column to 
Clarke's column, their size, exact orig'in, course and ter- 
mination in Clarke's column. Distinguish carefully here 
the well marked, fine-fibered zone of Lissauer. 
D. Spinal Cord: Cell Groups. 
1. Transverse section of the lumbo-sacral infant's spinal 
cord. Nissl's stain. 
Low power. Make a fairly large outline of the cord 
and outline faintly its gray matter. In the latter indicate MEMORANDA The Nervous System. 
153 
the following cell groups: (a) The large motor cells of 
the ventral horn. Distinguish in them the dorso-medial and 
ventro-medial groups, the ventro-lateral, dorso-lateral and 
central groups. What are the destinations of their axones? 
(&) The large-celled (magnocellular) groups. Two of these 
are present here: the pericornual (marginal) group around 
the dorsal horn and the central cells of the dorsal horn. 
These two groups are only represented by scattered cells, 
(c) The cells of the substantia gelatinosa of Rolando 
(nucleus sensibilis). These are very numerous small cells. 
(d) The diffuse cells, quite small, scattered more or less 
diffusely throughout the gray. 
2. Transverse section of the lumbo-sacral (infant's) 
spinal cord. Cajal's silver stain. 
Note especially the motor groups of the ventral horn 
and the cells of the gelatinosa of Rolando. Examine the 
latter high power. The other cells are not very distinct. 
3. Transverse section of the lower thoracic spinal cord. 
Nissl's stain. 
Repeat the observations made on section 1, noting the 
reduction in number of the motor cells of the ventral horn. 
Why are these fewer here? Note, in addition, the presence 
of the large celled basal group (nucleus magnocellularis 
basalis), or column of Clarke, and the intermedio-lateral 
group of preganglionic sympathetic cells in the lateral 
horn. What is the destination of the axones of these lattei' 
cells? Make a drawing similar to that of section 1. 
4. Transverse section of the lower thoracic spinal cord. 
Cajal's silver stain. 
Note the same points as in section 3. 
5. Transverse section of the cervical enlargement of the 
spinal cord. Nissl's stain. 
Note the same points as in section 3. Note the absence 
of the cells of Clarke's column and of the sympathetic group, 
also the increase of motor cells of the ventral horn as com- 
pared with the thoracic cord. Why? What are the des- 
tinations of these cells here? 
6. Transverse section of the cervical enlargement of 
the spinal cord. Cajal's silver stain. 
Note the cell groups observed in section 5, as far as 
visible. 
7. Transverse section of the cervical enlargement of the 
spinal cord. Weigert's myelin stain. MEMORANDA The Nervous System. 
155 
Note the general shape of the cord and of its gray, and 
as far as possible locate the cell groups. 
8. Transverse section of the upper cervical spinal cord. 
Weigert's myelin stain. 
Note that the ventral horn is much smaller than in the 
cervical enlargement. Why? In the very high cervical 
segments, the dorsal horn becomes larger. 
Note also the presence of lateral roots, i.e. fibers pass- 
ing dorsally from the ventral horn in the gray where some 
of the fibers turn longitudinally and others pass laterally or 
dorso-laterally, to emerge on the lateral surface of the cord 
at a variable distance ventrally to the zone of Lissauer. 
These are the roots of the spinal accessory or cranial nerve 
XI. 
In general what are the variations in size and shape of 
the gray matter in the various levels of the cord and to what 
do you attribute them? What are the variations in amount 
of white matter and to what do you attribute them ? 
E. Spinal Cord: Fiber Tracts. 
1. A series of transverse sections of the thoracic, cervical 
enlargement, and upper cervical segments of a spinal cord 
in which the lumbo-sacral region had been crushed some 
time previously. Weigert's myelin stain. (To be com- 
pared with section 3 below). 
Naked eye, ocular and low power. Note that there are 
lig'ht, comparatively unstained areas in the white columns, 
especially in the dorsal white column. In general to what 
are these due? What appearances in the sections prove 
that the lesion affected the cord itself and not simply its 
roots in the cauda equina? In each dorsal white column 
note that in the lowest section (the one nearest the injury) 
practically the whole dorsal column is light, possibly in- 
cluding a portion of the zone of Lissauer. In the following 
sections the light area of degeneration becomes progress- 
ively smaller and also becomes separated from the dorsal 
horn by an increasingly larger stained, undegenerated, area. 
How do you account for these changes in the degenerated 
and undegenerated areas in the dorsal column? What 
do they prove as to the positions and lengths of the 
ascending arms of the dorsal root fibers entering at var- 
ious levels of the cord? 
In the ventro-lateral white columns are less well marked 
light (degenerated) areas. These are more evident and 
extensive in the lower levels. In these levels the largest MEMORANDA The Nervous System. 
157 
dark (undegenerated) area is in the lateral column along- 
side the dorsal horn. This area is occupied principally by 
the lateral pyramidal and rubro-spinal tracts. Why should 
they show no degeneration? Outside the lateral pyramidal 
tract and next to the periphery there can be seen slight 
evidences of degeneration (compare with a similarly stained 
normal cord). This area is occupied by the dorsal spino- 
cerebellar tract. Why does it not show more degenera- 
tion? Further ventrally the area of partial degeneration 
is wider and more marked. The peripheral portion of this 
area is occupied by the ventral spino-cerebellar tract and 
the medial part, protruding into the rest of the white 
column, is occupied by the lateral spino-thalamic tract. Ex- 
tending medially into the ventral white column is an ill- 
defined area of diffuse degeneration which is occupied by 
the "medial spino-thalamic" tract. Note that in the higher 
levels of the cord these areas tend to become less pro- 
nounced and less wide spread. How do you account for 
this? Draw an outline of each section and outline its gray. 
Indicate by shading the degenerated areas and label the 
tracts they represent. 
2. Transverse section of a high cervical segment of a 
spinal cord in which the low cervical region had been 
crushed some time previously. Weigert's myelin stain. 
Naked eye, ocular and low power. Note the area of 
degeneration in each dorsal white column, separated from 
the dorsal horn by an undegenerated area. What fibers 
normally occupy the degenerated area? What are the 
fibers in the undegenerated area? How do the degenerated 
and undegenerated areas compare in size with the similar 
areas in a section of the same level in 1 ? How do you 
account for this difference? Are there any undegenerated 
fibers in the degenerated area? What does this prove? 
Does the degenerated area correspond to the column of Goll 
in either section? What does this prove as to the origin 
of the fibers composing the columns of Goll in the high 
cervical cord? 
In the ventro-lateral white columns note the same areas 
of degeneration noted in series of sections 1; also note 
that they are all much more marked, except the area of the 
medial spino-thalamic, especially the area of the dorsal 
spino-cerebellar tract which is very light (i.e., free from 
normal fibers) and well defined. How do you account for 
this difference between this section and the same level in 1 ? 
Does the medial spino-thalamic area differ much from the 
corresponding level in 1 ? What two alternative conclusions MEMORANDA The Nervous System. 
159 
could you draw from this as to either the level of origin or 
length of fibers in this area? Note in many of these sections 
the presence of undegenerated fibers in the ventral part of 
the dorsal spino-cerebellar tract. These are aberrant fibers 
of the lateral pyramidal tract. Why have they escaped de- 
generation? Note the general presence of the dorsal and 
ventral root fibers and look for any lateral rootlets of the 
spinal accessory nerve which may be present. Draw an 
outline of the cord and of its gray and indicate by shading 
the degenerated areas. Label the tracts they represent. 
Indicate also the dorsal and ventral root fibers and any 
spinal accessory root fibers, if present. 
3. Transverse sections of various thoracic segments of a 
spinal cord in which the lumbo-sacral region was crushed 
a short time previously. Marchi's osmic stain of degen- 
erating myelin. Compare carefully with the corresponding 
level in 1. 
Ocular and low power. Note in general the areas oc- 
cupied by degenerating medullated fibers, indicated by the 
presence of black granules. 
Select the section of the lowest level (i.e. the one nearest 
to the injury) by inspection of the dorsal white columns in 
each section. In this section, besides the degeneration 
throughout the dorsal columns, all of the ventro-lateral 
columns contain scattered black granules excepting an area 
in the dorsal part of the lateral column corresponding to 
the darkest area in the lowest levels in series 1. This is 
obviously the area of the lateral pyramidal tract. Com- 
pare this section with one of the sections of a higher level. 
In the latter what differences are there in the dorsal white 
column? Compare with series 1 and explain. In the ventro- 
lateral white columns the black granules are now confined 
to the areas previously described (series 1-compare sec- 
tions of corresponding levels) as occupied by the dorsal 
and ventral spino-cerebellar and the lateral and medial 
spino-thalamic tracts. The same difference between the low 
and higher thoracic levels was seen, less distinctly, in series 
1. How do you account for it? What degenerating fibers 
are present in the low level which are not present in the 
higher level? In addition to the tracts mentioned above, 
black granules may be seen in the ventral white columns 
adjacent to the ventral longitudinal sulcus, the sulco- 
marginal tract of Marie. 
In general, what kind of degeneration is present in 1, 2 
and 3? Upon what law does it depend? Are these degen- 
erations of ascending or descending tracts or both? Do MEMORANDA The Nervous System. 
161 
they throw any light upon the direction of conduction? 
Why? 
4. Transverse section of thoracic and lumbo-sacral seg- 
ments of a spinal cord in which the lower cervical segments 
had been crushed some time previously. Weigert's myelin 
stain. 
Naked eye, ocular and low power. In the section of the 
highest level (i.e. just below the injury) note any area of 
softening in the dorsal white columns due directly to the 
injury. Note besides this in the dorsal columns areas of 
degeneration. These may in part be due to the close prox- 
imity of the lesion but in part are probably true descending 
secondary degenerations of such systems as the comma and 
septo-marginal tracts. In the ventro-lateral white columns 
note the extensive areas of degeneration involving nearly all 
of the dorsal portion of the lateral column and extending 
around the margin of the rest of the ventro-lateral columns. 
It is evident at once that the degeneration includes the 
ascending spino-cerebellar and part at least of the spino- 
thalamic tracts and that there must therefore be more than 
a pure secondary (descending) degeneration. Why? The 
degeneration of these tracts is of a traumatic, primary char- 
acter, but in some cases also involve whole neurones owing 
to the severity of the injury and its proximity to the neu- 
rone body. If the degeneration of the ascending tracts 
(compare 1, 2 and 3) be subtracted from the degeneration 
present there will be found to be an extensive degeneration 
(secondary and descending) in the dorsal part of the lateral 
column between the dorsal spino-cerebellar area and the 
dorsal horn. This is the area which was darkest in 1 and 2 
and contained no granules in 3. It is the area of the lateral 
or crossed pyramidal and rubro-spinal tracts. In the ventral 
portion of the lateral column and in the ventral column, if 
the area of the ventral spino-cerebellar, and spino-cerebellar 
and spino-thalamic tracts be subtracted (compare carefully 
1, 2 and 3) there will be found to be a considerable remain- 
der of true descending degeneration, especially at the mar- 
gin of the cord. In the lateral column this is the area oc- 
cupied by uncrossed Deitero-spinal and other vestibulo- 
spinal fibers, in the ventral column it is the area occupied 
by uncrossed and crossed Deitero-spinal or vestibulo-spinal 
fibers, possibly by colliculo-spinal fibers, by fibers from the 
interstitial nucleus in the midbrain and by the medial or 
uncrossed pyramidal tract. Note that the area of degenera- 
tion in the ventral column adjacent to the ventral longitud- 
n MEMORANDA The Nervous System. 
163 
inal sulcus is separated from the latter by a thin rim of 
undegenerated fibers. These are probably the ascending 
fibers of the sulco-marginal tract noted in 3. Note that 
there are some intact fibers in the dorsal part of the dorsal 
spino-cerebellar tract. How do you explain this? Can 
you draw any conclusions as to the possible arrangement 
of the fibers in the dorsal spino-cerebellar tracts? What 
conclusions? 
The preceding degenerations thus principally involve the 
long tracts. Note that the white matter of the ventro- 
lateral columns adjacent to the gray is much less affected. 
By comparing with the ascending degenerations in 1,2 and 
3, in which these areas are also unaffected, it is evident that 
they are the areas of the short, intersegmental or spino- 
spinal fibers often called, together with some longer fibers, 
the ground bundles of the cord. They are naturally not 
entirely free from degeneration (fibers from cell bodies in 
lesion and retrograde degeneration of the fibers entering 
the lesion). The dorsal portion, constituting the thin un- 
degenerated layer between the lateral pyramidal tract and 
the dorsal horn is often called the lateral limiting layer. 
Make an outline of the cord and its gray and indicate by 
shading the degenerated areas. Label the tracts occupying 
the degenerated areas. Note and indicate in the drawing 
the presence of the lateral horn. In the lower thoracic 
section note that the degenerated areas have diminished 
and that in those sections not too low the dorsal spino- 
cerebellar tract contains more intact fibers. Why? 
In the lumbo-sacral section note the diminished lateral 
pyramidal tract now lying next to the periphery of the 
cord. Why is it smaller? Why is it no longer separated 
from the periphery of the cord by the dorsal spino-cerebellar 
tract? 
5. Transverse section of the cervical enlargement of the 
spinal cord of a hemiplegic. Weigert's myelin stain. 
Naked eye, ocular and low power. Note the lighter 
areas in one lateral and one ventral white column, formerly 
occupied by the crossed and uncrossed pyramidal tracts. 
Note that they are on opposite sides of the cord. Do you 
think this degeneration could have been caused by a lesion 
in the cord? Why? Any suggestions as to the explana- 
tion? 
In general, the student should not only learn the posi- 
tions of the tracts but should understand exactly how the 
degenerations studied in these sections have been produced. MEMORANDA The Nervous System. 
165 
6. Transverse section of the cervical spinal cord of a 
foetus of about 8 months. Weigert's myelin stain. Illus- 
trating the myelogenetic method of distinguishing fiber 
tracts. 
Naked eye, ocular and low power. Note the unstained 
areas occupied by the as yet non-medullated axones of the 
lateral and medial pyramidal tracts. Note also the asym- 
metry of the latter. Note also in general the comparatively 
large area occupied, for this level (compare other cervical 
sections of adult cord), by the gray matter. 
Draw an outline of the cord and its gray and indicate 
by shading the positions of the non-medullated pyramidal 
tracts. Also indicate the boundary between the columns of 
Goll and Burdach (fasciculus gracilis and fasciculus cune- 
atus) which are well marked in this section. 
7. Note the light areas occupied by the non-medullated 
or only partly medullated fibers of the lateral pyramidal 
tracts in the previous sections of the infant's cord stained 
by Weigert's myelin stain. 
8. Transverse section of the cervical enlargement of the 
spinal cord of an infant (5 weeks). Weigert's myelin stain. 
Many of the tracts can be distinguished by their relative 
degrees of myelinization. Compare carefully with the pre- 
ceding sections 1 to 6. 
Naked eye, ocular and low power. Note the dark nar- 
row band occupying the periphery of the lateral white 
column and gradually getting thinner ventrally. What 
tracts occupy this area? (Compare 2.) Note the thin dark 
area next to the gray laterally to the dorsal horn, rather 
abruptly widening at the upper border of the ventral horn 
and thence passing around the ventral horn as a wide dark 
area. What tracts occupy this area? (Compare 4.) Note the 
large light area occupying the dorsal part of the lateral 
white column. What tract occupies this area? (Compare 
2, 4, 5 and 6.) The other tracts can be located with refer- 
ence to these by comparison with the preceding sections. 
Note also in this section the various parts of the gray, 
the dorsal and ventral roots and the commissures, and dis- 
tinguish the columns of Goll and Burdach. Note also the 
processus reticularis, a mixture of gray and white situated 
laterally to the dorsal horn. Draw a large outline of the 
cord and its central canal and gray, indicating also the pro- 
cessus reticularis, the boundaries between the columns of 
Goll and Burdach and the dorsal and ventral root fibers. 
In this outline indicate by shading the relative depths of MEMORANDA The Nervous System. 
167 
staining of the white matter and locate all the previous 
tracts of the cord. Label. 
Before taking up the structure of the various parts of the 
brain the student should be thoroughly familiar with the 
tracts of the cord, their origins, courses and locations in the 
cord and their terminations. In addition to this, he should 
know the path of which each tract is a part, in detail that 
portion of each path lying in the body and cord, and in a 
more g'eneral way, the higher continuation and destination 
or origin of each path in the brain. 
In general, in the study of the sections of the brain 
as well as of the cord, the student should, in addition to 
noting the location of nuclei, tracts, courses of fibers, etc., 
endeavor to comprehend the connections of which they are 
a part and the functional significances of these connections. 
For each nucleus or mass of gray, i.e. for each group of 
neurone bodies, he should endeavor to learn: (1) What 
fibers originate in it and what is their termination? (2) 
What fibers terminate in it and what is their origin? It 
is obvious that each nucleus must have this double con- 
nection. (3) What is the path of which it is a part (be- 
ginning of the path, neurone groups composing it and its 
destination) ? (4) What is the functional significance of 
the nucleus and of the path of which it is a part and what 
is the effect of injury to either? For every tract or bundle 
of fibers he should endeavor to learn : (1) What is its origin, 
i.e. from what neurone bodies do its fibers arise? (2) What 
is its termination, i.e. among wihat neurone bodies do its 
fibers end? (3) What is the path of which it is a part (be- 
ginning of the path, neurone groups composing it and its 
destination) ? (4) What is the functional significance of 
the tract and of the path of which it is a part and what is 
the effect of injury to either? These questions must be 
regarded as applying to the nuclei and tracts in each one 
of the following sections of the brain, even though they 
are not, for the sake of brevity, repeated in each section. 
The student should also compare the external markings 
or configuration of each section with the corresponding 
region in a brain or brain model or, if not available, with 
illustrations of the same. 
F. Rhombencephalon (Medulla Oblongata or Bulb, Pons, 
Cerebellum and Isthmus). 
1. Transverse section of the medulla of an infant through 
the decussation of the pyramids. MEMORANDA The Nervous System. 
169 
Naked eye, ocular and low power. Note the shape of 
the section. Next to the median line dorsally is the emi- 
nence produced by the fasciculus gracilis or column of Goll, 
separated laterally by the paramedian fissure from the fasci- 
culus cuneatus or column of Burdach. Laterally to the 
fasciculus cuneatus is a slight eminence known as the 
tuberculum cinereum (gray tubercle) or tuberculum trige- 
mini or tubercle of Rolando. Why are each of these names 
descriptive?' The ventral fissure is shallower owing to 
the decussating pyramidal fibers. Fibers of the most an- 
terior dorsal and ventral cervical spinal roots may still be 
present. Look for spinal accessory roots (see also section 
E. 2). Note that the dorsal gray horn has increased in 
size. Why? (See below.) Note that the ventral horn is 
cut off from the rest of the gray by the masses of pyramidal 
fibers passing through the intermediate gray. In addition 
to this change, the longitudinal fibers of the lateral white 
column adjacent to the gray (short tracts) are becoming 
mingled not only with the gray of the dorsal horn, as in the 
processus reticularis of the cord, but also with the adjacent 
intermediate and ventral gray. This intermingling of short 
intersegmental tracts and gray is known as the gray retic- 
ular formation (formatio reticularis grisea). Note that the 
central gray extends further dorsally and, in the higher sec- 
tions through the pyramidal decussation, a protrusion from 
it extends into the fasciculus cuneatus. There may also be 
seen a mass of gray appearing within the fasciculus gracilis 
(see next section). 
The fasciculus gracilis and cuneatus are well marked 
off from each other by a septum. Note that the zone of 
Lissauer (light-staining fibers) appears to have increased in 
size. This is due to the presence of descending trigeminal 
root fibers (tractus spinalis radicis trigemini or spinal V). 
What is the origin of their fibers? Study (high power) 
their relation to the dorsal horn, comparing with the cord. 
Outside the zone of Lissauer are usually to be seen dark 
staining coarse fibers. They are obviously bundles from 
what tract? The continuation of the lateral white column 
has now lost its lateral pyramidal tract, the fibers of which 
are either imbedded in the region of the intermediate gray 
or are crossing the median line to the opposite ventral white 
column where they join the uncrossed pyramidal tract. The 
ventral white column is obviously increased in size by the 
accession of the light staining pyramidal fibers. What im- 
portant physiological fact is explained anatomically by this 
crossing? Besides the three changes mentioned in the MEMORANDA The Nervous System. 
171 
lateral column (what are they?), the remainder has the 
same arrangement of its constituent ascending dorsal and 
ventral spino-cerebellar and lateral spino-thalamic tracts 
and descending rubro-spinal and vestibulo-spinal tracts 
(origins, terminations, paths?). A peripheral light area at 
about the junction of the lateral and ventral columns is 
occupied by the tract of Helweg (possible origin and 
termination ?). 
Encircling the ventral horn note the dark stained U- 
shaped mass of fibers, the medial portion of which is ob- 
viously the continuation of the ventral columns of the cord 
and containing the same tracts (vestibulo-spinal, colliculo- 
spinal, tract from interstitial nucleus, medial spino-thalamic 
and short intersegmental tracts, in addition to the uncrossed 
pyramidal which has been increased by fibers from the 
lateral pyrarhidal tract as already mentioned. Origins, 
terminations, paths? See general paragraph preceding this 
section). Laterally the U-shaped mass of fibers is seen to 
spread out into the lighter staining mass of the lateral 
column already described. 
Draw an outline of the section, or use the outline given 
out, and indicate by shading (using lead pencil and not 
crayon) the gray and the variously stained longitudinal 
fibers. Draw carefully all transverse fibers. On one side 
of the outline colors may be used to indicate more schem- 
atically the various tracts, but one side should be drawn 
as it appears. 
Label all external markings, tracts, masses of gray, etc. 
It would be advisable for the student to make a synopsis 
covering the points mentioned in the general paragraph 
preceding this section. 
2. Similar section of an adult medulla. Weigert's mye- 
lin stain. 
Note the same points, many of which are not so distinct 
owing to the increased myelinization, especially of the 
pyramidal tract and the plexuses in the gray. 
3. Similar section of the medulla. Nissl's stain. 
Study the cell groups in the above masses of gray. At 
this level they do not differ much from those in the cord. 
Some of the nuclei mentioned in 5 may be present. A 
separate drawing may be made or the cell groups indicated 
in the drawing of 1. 
4. Similar section of the medulla. Cajal's silver stain. 
Repeat, as far as possible, the observations made in 1, 
2 and 3. MEMORANDA The Nervous System. 
173 
5. Transverse section of the medulla of an infant through 
the decussation of the medial fillet or medial lemniscus. 
Weigert's myelin stain. 
Naked eye, ocular and low power. Note the external 
markings : The eminences produced by the fasciculi gracilis 
and cuneatus are more prominent (why?), and are now 
called the clava and cuneus respectively. The tubercle of 
Rolando is also more prominent. Why? Ventrally there 
are now two conspicuous prominences, one on each side, 
the pyramids. Explain their size. Are there any decus- 
sating pyramidal fibers? Compare with a brain, brain 
model or illustrations of the same. 
The dorsal horn, or its continuation, is still larger. Why? 
In addition two new masses of gray have appeared, one in 
the fasculus gracilis (nucleus fasciculi gracilis or nucleus 
of the column of Goll) and the other in the nucleus cune- 
atus (nucleus fasciculi Guneati or nucleus of the column of 
Burbach). What are their relations to the columns ? Study 
(high power) indications of this relation and indicate it in 
the drawing. What is the relation of the dorsal horn to 
the spinal V? Study (high power) indications of this rela- 
tion and indicate it in the drawing. The intermediate gray 
and ventral horn are now about completely intermingled 
with longitudinal (transversely cut) bundles of nerve fibers 
besides being traversed by the usual transversely running 
fibers. This mixture, the gray reticular formation, has thus 
increased. In the gray reticular formation, in addition to 
the diminished remnant of the ventral horn cells, are the 
ventral motor nucleus of nerve X (nucleus ambiguus) and 
possibly other vagus nuclei, various nuclei known as the 
nuclei reticularis and, at the lateral border, the nucleus 
funiculi lateralis. None of these nuclei are easily distin- 
guishable at this level in Weigert preparations. Note the 
external arcuate or arciform nuclei, forming indentations in 
the outer borders of the pyramids. What are their prob- 
able connections? In some of the higher sections of this 
level, the inferior olivary nucleus, especially its accessory 
portion, may be seen in the vicinity of Helweg's tract (see 
next level). The central gray is large and may now con- 
tain the following nuclei (not easily made out, at this level, 
with the Weigert stain) : the nucleus commissuralis (IX and 
X), the dorsal motor nucleus of nerve X, possibly the dorsal 
sensory nucleus of nerve X and the nucleus of nerve XII. 
They are better distinguished in the next section. 
The dorsal white columns show some diminution, es- 
pecially the column of Goll? Why? From the nuclei of MEMORANDA The Nervous System. 
175 
the columns of Goll and Burdach fibers can be seen emerg- 
ing which pass ventrally, curving around the central gray 
(as internal arcuate or curved fibers) and decussating ven- 
trally to it. Note carefully their apparent destination. It 
will be seen that they tend to insert themselves between the 
pyramids and the darkly stained continuation of the ventral 
white columns of the cord. Here, as subsequent sections 
will show, they turn cephalad and build up a large longi- 
tudinal tract, the medial fillet or medial lemniscus. The 
decussating fibers should be sharply distinguished from the 
continuations of the ventral columns which are laterally 
to them. What is the relation of these fibers to the nuclei 
of the columns of Goll and Burdach, and what is the general 
significance of the latter? Of what path are these struc- 
tures a part? What important physiological fact is ana- 
tomically explained by this decussation? Note, in this and 
higher sections, the lightly stained lateral portion of the 
nucleus cuneatus. This is the-external cuneate or von Mona- 
kow's nucleus, probably having different connections from 
the rest of the cuneate nucleus. The spinal V is larger. 
Why? The continuation of the lateral column is practically 
unchanged. Indicate its constituent tracts in the labels of 
the drawing. The tract of Helweg is more conspicuous. 
The pyramidal tracts have been mentioned. Laterally to 
the pyramidal tracts may be seen the dark mass of fibers 
constituting the continuation here of the ventral columns 
of the cord (excepting the pyramidal tract). What are its 
constituent tracts? Indicate them in the labels of the draw- 
ing. The L-shaped lateral extension of this mass contains 
the more lateral Deitero- or vestibulo-spinal fibers and the 
medial spino-thalamic tract. Further laterally it merges 
into the continuation of the lateral column of the cord. In 
many sections at this level there can be seen transverse 
fibers passing around in the outer border of the section. 
Such curved fibers are called superficial or external arcuate 
fibers in distinction from deep or internal arcuate fibers. 
The superficial arcuate fibers at this level are probably fibers 
to the cerebellum (via restiform body, see later sections) 
and in part probably originate from the nuclei funiculi 
lateralis and the arcuate nuclei. Study carefully (high 
power) the indications of the former shown by fibers pass- 
ing dorsally, near the surface, from the region of the lateral 
column and thereby gaining a position, together with fibers 
from the dorsal spino-cerebellar tract, external to the spinal 
V. This constitutes the first indication of the formation of 
the restiform body (see next level). MEMORANDA The Nervous System. 
177 
Draw and label according to directions given for sec- 
tion 1. 
6. Transverse section through the same level of an adult 
medulla in a case of crush of the lower cervical cord. Weig- 
ert's myelin stain. 
Naked eye, ocular and low power. Note especially the 
disappearance or degeneration of the fibers of the column of 
Goll and the partial disappearance of .those of the column 
of Burdach. Why this degeneration? What fibers of the 
column of Burdach have disappeared and what are intact? 
Note that the internal arcuate fillet fibers and the fillet itself 
are intact. Why? Note the presence of fibers in the nuclei 
of the columns. What are they? Note the degeneration in 
the continuation of the lateral columns of the cord. What 
tracts here are degenerated and why? Is the spinal V de- 
generated? Why? A drawing may be made showing es- 
pecially the above points. 
7. Similar section of normal adult medulla. Weigert's 
myelin stain. 
Follow the directions given for section 5. Note changes 
in myelinization of fibers. 
8. Similar section of medulla. Nissl's stain. 
Locate and study the nuclei mentioned in section 5. 
Draw as directed in 3. 
9. Similar section of medulla. Cajal's silver stain. 
Repeat, as far as possible, the observations made on 
sections 5, 7 and 8. 
10. Transverse section of the medulla of an infant 
through the lower middle portion of the inferior olivary 
nucleus. Weigert's myelin stain. 
Naked eye, ocular and low power. Note that the central 
canal has widened out into the fourth ventricle, the roof of 
which is formed by the thin tela and plexus chorioideus 
(often torn away in the preparation). If present, note in 
the latter the outer vascular connective tissue portion 
formed by the pia and the layer of low epithelium lining 
its inner surface. What is the physiological significance of 
these thin-walled portions of the brain? What apertures 
are there in the chorioidea of the fourth ventricle and be- 
tween what cavities do these apertures form communi- 
cations? What is the general effect of the opening of the 
cord into the fourth ventricle upon the topographical rela- 
tions of the various structures of the medulla? In the floor 
12 MEMORANDA The Nervous System. 
179 
of the ventricle note the following markings: (1) The 
medial eminence (here containing the nucleus hypoglossi 
and therefore called the trigonum hypoglossi). (2) The in- 
ferior fovea, ala cinerea or trigonum vagi (the last name on 
account of structures connected with the vagus lying in this 
area). Why the terms inferior fovea and ala cinerea? (3) 
The sulcus limitans. (4) The area acustica, small here but 
large in higher levels. Laterally to this is the taenia form- 
ing the lateral boundary of the ventricle and the attachment 
of the chorioidea. Note on the external surface: (1) That 
the clava and cuneus have practically disappeared; (2) the 
restiform body; (3) the olive (due to the presence within 
of what structure?); (4) the postolivary furrow; (5) the 
preolivary furrow; (6) the pyramid. The vagus roots may 
usually be seen emerging in the postolivary furrow and the 
hypoglossus roots emerging in or near the preolivary fur- 
row. What kind of fibers are found in these nerves? What 
do they innervate? Compare with a brain, brain model or 
illustrations of the brain. 
Note the nucleus hypoglossi in the medial eminence. 
What do its fibers innervate? Study this nucleus care- 
fully (high power). Note the coarse root fibers emerging 
from it and passing ventrally. Trace them to their emerg- 
ence from the bulb. In addition note the numerous fine 
fibers in the nucleus. Note that they appear to enter the 
nucleus from its dorsal, lateral and ventro-medial sides. 
What is their general relation to the nucleus and from what 
sources do they probably ultimately come? What func- 
tional connections do they probably represent? Dorsal to 
the nucleus is the nucleus teretis or nucleus eminentiae 
medialis and dorso-laterally the nucleus intercalatus (ceph- 
alad of the nucleus hypoglossi, the nucleus prepositus). 
These nuclei are small,. small celled and difficult to dis- 
tinguish. They are probably intra- or intersegmental. Just 
dorso-lateral to the nucleus intercalatus is a small fine- 
fibered bundle, the tractus dorsalis tegmenti or dorsal longi- 
tudinal bundle of Schutz. What is its character? In the 
region of the trigonum vagi note the dorsal motor (pre- 
ganglionic sympathetic) nucleus of the vagus (large and 
small celled divisions) or nucleus alae cinereae. What do its 
fibers probably innervate? Note the fasciculus solitarius 
(descending arms of afferent root fibers of nerves VII, IX 
and X). Where are the cell bodies originating them and 
what do they innervate peripherally? Dorso-medial to this 
bundle, in the central gray, is the "sensory" nucleus of 
nerve X. Another (compact appearing) nucleus in this MEMORANDA The Nervous System. 
181 
region is the nucleus rotundus vagi. Ventro-laterally to 
the solitary fasciculus is the small ventral nucleus of the 
solitary fasciculus and dorsally to it the small dorsal nucleus 
of the solitary fasciculus. These nuclei cannot be distin- 
guished in all levels. What is the general character of these 
last three nuclei? Can you suggest any special function for 
each? Note the poverty of medullated fibers in the vagus 
nuclei in the central gray. What conclusions do you draw? 
Locate the nucleus ambiguus or ventral motor nucleus of 
the vagus, lying in the gray reticular formation. What do 
its fibers innervate? The vagus probably has another 
nucleus lying medially to the latter in the gray reticular 
formation whose preganglionic fibers pass to sympathetic 
ganglia which send fibers to glands (glandular or secretory 
nucleus). Trace, as far as possible, the vagus root fibers 
to and from these nuclei and to the solitary fasciculus. 
Through what structures do they pass? Beneath the area 
acustica note the medial vestibular nucleus and further 
laterally the descending vestibular root fibers and their 
nucleus. What is the origin of these fibers and what is 
their relation to the vestibular nuclei? The vestibular area 
is also called juxtarestiform. Why? What similarity or 
parallelism is there between the course of the roots of the 
trigeminus, vestibular and facialis-glossopharyngeo-vagus 
nerves? Why three separate systems? Study carefully 
(also high power) the internal arcuate fibers emerging from 
the vestibular and central gray (vagus) areas and passing 
ventro-medially. What is their general character? Can 
you suggest any reflex or other connections mediated by 
them? Note that laterally to the vestibular fibers and 
nuclei is still a remnant of the nucleus of the column of 
Burdach and possibly of the nucleus of the column of Goll. 
Are there any arcuate fibers from these nuclei? Note the 
diminished nucleus of the spinal V (continuation of the 
dorsal horn) and distinguish between the fibers of the spinal 
V and those of the large restiform body. What are the 
origins of the latter fibers? Of what general path do they 
form a part? 
Note-the continuation of the lateral column of the cord. 
What tracts are present in it here? Note the great extent 
of the gray reticular formation. Next to the median line 
and dorsal to the pyramids is a mass of longitudinal fibers. 
Which of these constitute the medial lemniscus and which 
the continuation of the ventral column of the cord? The 
latter is now called the medial or posterior longitudinal 
fasciculus. What fibers compose it? Does it occupy the MEMORANDA The Nervous System. 
183 
same position relatively to the central cavity which it oc- 
cupied in the cord? Note that the medial longitudinal fasci- 
culus and medial lemniscus are crossed by numerous trans- 
verse decussating fibers producing a reticulated appearance. 
This is sometimes called the white reticular formation (for- 
matio reticularis alba) in distinction from the gray reticular 
formation. Why is one called gray and the other white? 
The median line is called the raphe. Why? As far as you 
can tell what kinds of fibers are decussating here? Dorsal 
to the inferior olivary nucleus lie part of the vestibulo- 
spinal and the medial spino-thalamic tracts. The olivary 
nuclei, pyramids and medial fillet are thus virtually new 
structures added ventrally to the cord. Significance? Dis- 
tinguish in the inferior olivary nucleus the three parts, the 
medio-ventral and dorsal accessory and the main portions. 
Which portion or portions are the newer? Why? Trace 
the fibers from the olivary nuclei to the restiform bodies. 
Are they mainly crossed or uncrossed? What appearances 
in the section indicate this? Note and trace any super- 
ficial arcuate fibers present. Note the nuclei funiculi later- 
alis and the nuclei reticularis. What is the general signifi- 
cance of the latter? Of the former? Draw as directed in 1. 
11. Section of adult medulla similar to 10. Weigert's 
myelin stain. 
Note the same points as in 10, also compare the degree 
of myelinization of the pryamidal tracts and the myelinated 
fibers in various other areas deficient in myelinated fibers 
in 10. 
12. Section of medulla similar to 10. Nissl's stain. 
Study the cell groups mentioned in 10. Draw as directed 
in 3. 
13. Section of medulla similar to 10. Cajal's silver stain. 
Study the various points covered in sections 10, 11 and 12. 
14. Transverse section of an infant's medulla through 
the middle of the inferior olivary nucleus. Weigert's 
myelin stain. 
The structures present here are the same as those de- 
scribed in 10, excepting the disappearance of the nucleus 
cuneatus and changes in the sizes of other structures, es- 
pecially an increase of the inferior olivary nucleus, restiform 
body, descending vestibular root and nuclei and solitary 
fasciculus. 
If a drawing is made follow the directions given in 1. MEMORANDA The Nervous System. 
185 
15. Similar section of the adult medulla. Weigert's 
myelin stain. 
Note the differences between this and 14. 
16. Similar section of the medulla. Nissl's stain. 
If a drawing is made follow the directions given in 3. 
17. Similar section of the medulla. Cajal's silver stain. 
Study the various points covered in 14, 15 and 16. 
18. Transverse section of an infant's medulla through 
the entrance of the cochlear root of nerve VIII. Weigert's 
myelin stain. 
Naked eye, ocular and low power. Note that the fourth 
ventricle is much wider and in some sections its long lateral 
recesses may be seen extending ventrally in two prolonga- 
tions at the sides of the medulla. In some sections of 
somewhat higher levels, one or both sides of the medulla 
are continuous with the cerebellum, the section pass- 
ing in front or cephalad of the lateral recesses. Note 
the chorioid plexus protruding into the fourth ventricle 
and its lateral recesses. Note that the floor of the ven- 
tricle is now practically at right angles to the median line 
of the medulla. Note that the trigonum vagi has disap- 
peared. Why? Laterally to the medial eminence, the floor 
of the ventricle is occupied by the area acustica of which 
there are two portions, a medial vestibular (juxtarestiform) 
and a lateral protuberance, the acoustic tubercle (tuber- 
culum acusticum) which may be called cochlear. Why? 
Note the olive, post- and preolivary furrows, pyramids and 
ventral longitudinal sulcus. Compare with a brain, brain 
model or illustrations of the brain. 
Identify the dorsal cochlear nucleus (in the acoustic 
tubercle) the ventral or "accessory" cochlear nucleus and 
the cochlear root fibers entering the latter ventrally. What 
is the origin of the cochlear root fibers, what do they in- 
nervate and what is their relation to the cochlear nuclei? 
What is their function? In some sections (not constant) 
bundles of fibers pass from the acoustic tubercle across the 
floor of the ventricle, the striae acusticae. What do they 
represent? 
Usually the root fibers of the glossopharyngeus can be 
seen emerging. What are their origins and what do they 
innervate? Trace them inwards. Many go to the region of 
the fasciculus solitarius, now reduced in size. If the fasci- 
culus is very small note, in its former place, the prevagal 
nucleus gustatorius. What are its probable relation to the MEMORANDA The Nervous System. 
187 
glossopharyngeus, function and further connections? There 
may be some remnants of the dorsal motor and "sensory" 
nuclei of the vagus (and glossopharyngeus) mentioned in 10. 
Identify the nucleus ambiguus. Medial to it in the gray 
reticular formation, but not distinguishable, is the pregang- 
lionic sympathetic nucleus salivarius inferior. What does 
it innervate? Function? Note that the nucleus hypo- 
glossi has disappeared. Its place in the medial eminence is 
occupied by the nucleus prepositus. Beneath the area acus- 
tica (vestibular portion) distinguish the descending vesti- 
bular root fibers (much increased), their nucleus and the 
medial (triangular or "principal" or Schwalbe's) vestibular 
nucleus. Trace carefully (also high power) any internal 
arcuate fibers proceeding from the above vestibular and 
glossopharyngeal areas. What is their general significance 
and what are their various probable connections? 
Note the spinal V and its nucleus. Distinguish between 
the fibers of the spinal V and those of the massive resti- 
form body. Note the large convoluted principal portion of 
the inferior olivary nucleus and also the dorsal accessory 
portion. Trace carefully the fibers passing from the in- 
ferior olivary nucleus to the restiform body. Are they 
crossed or uncrossed? Why? Note the large gray re- 
ticular formation and the nuclei reticularis, also the nuclei 
funiculi lateralis. Note the continuation of the remnant of 
the lateral column of the cord beneath the postolivary fur- 
row. What tracts compose it? Their function? Effect of 
an injury here? Note the large medial fillets, lying between 
the inferior olivary nuclei, and dorsal to them the predorsal 
bundle (colliculo-spinal fibers) and the continuation of the 
rest of the ventral white column now called the medial 
longitudinal fasciculus. What fibers compose the latter? 
The remainder of the vestibulo-spinal fibers and the medial 
spino-thalamic tract lie dorsal to the inferior olivary 
nucleus. It will be noted that they still form the portion 
connecting the ventral and lateral columns as they do in the 
cord. Note the large pyramids and any superficial arcuate 
fibers which may be present. 
19. Similar section of the adult medulla. Weigert's 
myelin stain. 
Note the same points as in 18. 
20. Similar section of the medulla. Nissl's stain. 
Study the cell groups mentioned in 18. If a drawing is 
made, draw as directed in 3. MEMORANDA The Nervous System. 
189 
21. Similar section of the medulla. Cajal's silver stain. 
Note, as far as possible, the points observed in sections 
18, 19 and 20. 
22. Transverse section of an infant's rhombencephalon at 
the level of the caudal border of the pons and the emerg- 
ence of the vestibular, facial and abducens nerves. Weig- 
ert's myelin stain. 
Naked eye, ocular and low power. Distinguish in the 
whole neural tube the cerebellum, the pons (lighter stain) 
and the tegmentum. Which of the two latter is the older? 
Which contains the more fundamental neural mechanisms? 
What kind of a connection does the pons represent? 
Note the shape of the fourth ventricle. In its floor dis- 
tinguish medial eminence, sulcus limitans and area acustica. 
Projecting downward is the inferior vermis (nodulus) of 
the cerebellum. Note the presence of a portion of the 
plexus chorioidetis. Externally the outer portions of the 
cerebellum have been removed. Note the flocculus cere- 
belli at the sides. Note, if present, the emerging roots of 
the vestibular portion of nerve VIII, nerves VII and VI. 
Between the two former are sometimes seen the slender 
root of the portio intermedia VII (nerve of Wrisberg, 
glosso-palatine nerve). What kind of fibers are found in the 
vestibular, abducens and the two portions of the facial 
nerves? What do they each innervate and what are their 
respective functions? Compare with a brain, brain model 
or illustrations of the brain. 
Trace the vestibular root fibers inwards into the vesti- 
bular area. What becomes of them there? Where do they 
pass in relation to the restiform body and spinal V? Dis- 
tinguish the nucleus of Deiters, the medial vestibular nu- 
cleus (smaller here) and (usually at a somewhat higher 
level) the superior vestibular nucleus (of von Bechterew). 
Carefully study (also high power) and trace as far as pos- 
sible any internal arcuate fibers from this region. What 
in general do they represent? What are their probable con- 
nections? Carefully study (also high power) the motor 
facial nucleus. Note the coarse root fibers emerging from 
it. In what direction? Note the finer fibers within the 
nucleus and as far as possible note their sources. What 
are their probable ultimate sources and what functional 
connections do they represent? Identify any other portions 
of the facial roots which may be present. Note the root 
fibers of the abducens. They may be emerging or travers- 
ing the pons or pyramids or they may be imbedded in the MEMORANDA The Nervous System. 
191 
medial lemniscus according to the exact level of the section. 
(For the nucleus and deeper origin see next level.) 
Note the fibers of the restiform body now beginning to 
pass into the white matter of the cerebellum. What rela- 
tion do they have to the conspicuous nucleus dentatus 
cerebelli? Note the juxtarestiform fibers passing dorso- 
ventrally in the cerebellum medial to the nucleus dentatus 
(see next level). Distinguish the spinal V and its nucleus. 
In some sections ventral to the restiform body may be seen 
the cephalic extremity of the ventral cochlear nucleus and 
possibly fibers passing medially from it. In other higher 
sections only the latter can be seen, passing medially ven- 
tral to the spinal V. These are the trapezius fibers. What 
is their origin, termination and of what path are they a 
part? Note the superior olivary nucleus (and in some sec- 
tions the nucleus of the trapezoid body and parolivary 
nuclei). Can you make out any relation to the trapezius 
fibers? What is the relation of the superior olive to them? 
What change in shape has the medial lemniscus undergone? 
Why? Distinguish the posterior longitudinal fasciculus. 
Has it changed its position? At about this level it begins 
to receive ascending vestibulo-spinal fibers. To what? 
What other fibers does it contain? Have you seen any 
evidence of its receiving fibers from the vestibular nuclei? 
Locate the continuation of the lateral column. Does it 
occupy the same position as formerly? What tracts com- 
pose it? Note the complete disappearance (or diminution) 
of the inferior olivary nucleus. Note in the area previously 
occupied by it, between superior olivary nucleus and medial 
lemniscus, a diffuse bundle of fibers, the central tegmental 
tract. What is its relation to the inferior olivary nucleus? 
Note the large gray reticular formation and its nuclei 
(nuclei reticularis). 
In the pons distinguish the gray masses (the pontile 
nuclei; what fibers do they receive and originate?), the 
longitudinal fibers (what are they?), the transverse fibers 
(what are they, what is their origin and destination and of 
what connection or path are they a part?) and the per- 
pendicular fibers. Distinguish the continuation of the 
transverse pontile fibers into the white matter of the cere- 
bellum. Are they located externally or internally to the 
other connections? Why? 
Draw as directed in 1. 
23. Similar section of the adult medulla. Weigert's 
myelin stain. MEMORANDA The Nervoxts System. 
193 
Observe the points mentioned in 22, noting any differ- 
ence in myelinization or otherwise. 
24. Similar section of the medulla. Nissl's stain. 
Study the cell groups mentioned in 22. If a drawing is 
made, draw as directed in 3. 
25. Similar section of the medulla. Cajal's silver stain. 
Study the various points covered in 22, 23 and 24. 
26. Transverse section of the infant's rhombencephalon 
at the level of the nucleus of nerve VI, deeper portions of 
the roots of VI and VII and the emergence of the afferent 
portion of nerve V. Weigert's myelin stain. 
Naked eye, ocular and low power. Note the fourth ven- 
tricle, the medial eminences on its floor, its general shape 
and diminished size. Note the three great divisions of the 
neural tube: cerebellum, pons and tegmentum. Note the 
emergence of nerve V. What do its fibers innervate? 
Compare with a brain, a brain model or illustrations of the 
brain. 
Note the root fibers of nerve VII. In what places do 
you see them ? Connect with their position in the previous 
sections. In the lateral portion of the medial eminence, 
note the nucleus abducentis, forming part of the eminentia 
abducentis (and facialis, why the latter?). Trace its fibers, 
the root fibers of the VI, ventrally through the tegmentum 
to the medial lemniscus. Connect them here with their 
position in previous sections and reconstruct the whole 
central course of the roots. Is there any "kink" in their 
course? Where and why? What fibers does the nucleus 
VI receive? Do you see any evidences of them (also use 
high power) ? Note that the nucleus of the spinal V has 
become somewhat broken up and that the spinal V is pass- 
ing out to the ventro-lateral surface of the pons. What is 
the proper anatomical interpretation of this appearance? 
What is the origin of these fibers and their central course 
as far as you have studied them ? 
Note the superior olivary nucleu-s and distinguish the 
lateral fillet or lateral lemniscus (not very distinct as yet) 
dorso-laterally to the superior olivary nucleus. What is its 
origin and termination and of what path is it a part? Are 
there any decussating trapezius fibers present? Note the 
fibers connecting the vestibular (juxtarestiform) region and 
cerebellum. In the cerebellum they pass upward between 
the now diminished nucleus dentatus and ventricle. Fur- 
ther forward some pass around outside the superior ped- 
13 MEMORANDA The Nervous System. 
195 
uncle (uncinate bundle). Note that near the medial upper 
part of the nucleus dentatus is another nucleus, the nucleus 
emboliformis. Dorso-medial and also ventral to this, in 
some sections, can be seen the small round nuclei globosi 
and, probably better in the next level, there is in the roof 
near the median line on each side the larger nucleus tecti 
or nucleus fastigii (the nucleus of the roof or of the peak. 
Why these names?). Distinguish the fibers of the resti- 
form body. How are they situated with reference to the 
nucleus dentatus? Distinguish in the cerebellum the pon- 
tile or middle peduncular fibers. Note that as the nucleus 
dentatus diminishes it is replaced by a mass of fibers lying 
next to the ventricle and passing forward. This is the 
superior cerebellar peduncle (brachium conjunctivum). 
What are the three cerebellar peduncles, what are the origins 
and terminations of the fibers composing them and of what 
cerebellar paths are they a part? What is the general 
meaning of the terms peduncle, brachium (brachia) and 
crus (crura)? 
Note in the now larger pons the nuclei pontis and the 
longitudinal, transverse and perpendicular pons fibers. 
Origins and terminations? The transverse fibers are some- 
times distinguished as dorsal or deep, middle, and ventral 
or superficial, the middle interlacing ones forming the 
stratum complexum. 
Note the medial lemniscus-, the medial longitudinal fasci- 
culus and locate the continuation of the lateral column of 
the cord. What tracts are present in the latter here? Note 
the gray reticular formation, its nuclei and the central teg- 
mental tract, now assuming a position near its center. 
Draw as directed in 1. 
27. Similar section of the adult rhombencephalon. 
Weigert's myelin stain. 
Observe the points mentioned in 26, noting any differ- 
ences. 
28. Similar section of the rhombencephalon. Nissl's 
stain. 
Study the cell groups mentioned in 26. If a drawing is 
made, draw as directed in 3. 
29. Similar section of the rhombencephalon. Cajal's 
silver stain. 
Study the various points covered in 26, 27 and 28. 
30. Transverse section of the infant's rhombencephalon 
at the level of the nucleus and exit of the efferent (motor) 
root (portio minor) of nerve V. Weigert's myelin stain. MEMORANDA The Nervous System. 
197 
Naked eye, ocular and low power. Note the cerebellum, 
pons and tegmentum, also that the only connection between 
the cerebellum and the rest of the neural tube is by means 
of the now fully formed superior cerebellar peduncle, now 
beginning to pass ventrally into the tegmentum and form- 
ing here the lateral wall of the fourth ventricle. Note the 
emergence of the portio minor of nerve V. What does it 
innervate? Compare with a brain, brain model or illustra- 
tions of the brain. 
Note the motor nucleus (nucleus masticatorius, why so 
named?) of the trigeminus and the motor root fibers pass- 
ing from it to the periphery. Note also that some of the 
fibers come from a small bundle medial to the ventral bor- 
der of the superior peduncle. These constitute the mesen- 
cephalic root of nerve V. Try to distinguish the rather 
large rounded cells near the ventricle from which these 
fibers originate, the mesencephalic nucleus of nerve V. 
What is there peculiar about its position for a nucleus 
whose axones pass outside the central nervous system? 
What conclusions might be drawn as to the character of 
this nucleus? Note the "principal sensory nucleus" of 
nerve V. What is its relation to the nucleus of the spinal 
V and to the afferent trigeminal fibers? Look for any evi- 
dences of a secondary trigeminal tract (what is meant by 
"secondary tract"?) passing across near the floor of the 
ventricle. Note the disappearance of the abducens nucleus. 
Is there any portion of the root fibers of nerve VII present? 
Reconstruct the wfiole central course of the motor root of 
nerve VII and especially its position with reference to the 
nucleus abducentis. Note the disappearance of all vesti- 
bular nuclei. 
Note the nuclei fastigii in the cerebellum. Is there any 
nucleus dentatus present? What fibers do these nuclei re- 
ceive and originate? Of what paths are they a part? Note 
that the pyramidal tracts in the pons are now broken up 
into a number of bundles. By what? Note the nuclei 
pontis and the perpendicular and transverse fibers of the 
pons, the latter no longer passing into the cerebellum. Note 
the medial lemniscus, lateral lemniscus, medial longitudinal 
fasciculus, reticular formation and its nuclei and the central 
tegmental tract. About at this level the ventral spino- 
cerebellar tract passes dorsally and assumes a position ex- 
ternal to the superior cerebellar peduncle. What tract or 
tracts are here left in the continuation of the lateral 
column? Draw as directed in 1. MEMORANDA The Nervous System. 
199 
31. Similar section of the adult rhombencephalon. 
Weigert's myelin stain. 
Observe the points mentioned in 30, noting any differ- 
ence. 
32. Similar section of the rhombencephalon. Nissl's 
stain. 
Study the cell groups mentioned in 30. If a drawing is 
made, draw as directed in 3. 
33. Similar section of the rhombencephalon. Cajal's 
silver stain. 
Study the various points mentioned in 30, 31 and 32. 
34. Vertical section through the cortex of the cerebellum 
and subjacent white matter. Cut transversely to the cere- 
bellar folia or laminae. Nissl's stain. 
Naked eye, ocular and low power. Note the pia mater 
enveloping the branching laminae. In each lamina note an 
external lighter layer (molecular or plexiform layer), an 
inner darker layer (granular or nuclear layer) and a lighter 
core (the white matter). On examination with the ocular 
or low power note the single row of widely spaced, large 
pear-shaped cells between the molecular and granular 
layers, the cells of Purkinje. The three layers (molecular, 
Purkinje and granular) constitute the external gray or 
cortex of the cerebellum. 
Low power and high power. Note that there are com- 
paratively few nuclei in the molecular layer, the nuclei of 
the stellate cells. The cytoplasm, especially of the inner, 
larger stellate (basket) cells is distinguishable. Study care- 
fully the Purkinje cells, their nucleus, cytoplasm and 
chromophilic bodies. Are the latter like those in the lower 
motor neurones? Study the cells of the granular layer. 
Note the two kinds of nerve cells, the caryochrome granule 
cells and a few large somatochrome cells, Golgi type II or 
the van Gehuchten cells. What is the difference between 
these two types? Note that the granule cells are not uni- 
formly distributed but that there are numerous small spaces 
free from them, the "glomeruli." Distinguish the somewhat 
larger nuclei of the neuroglia cells, especially at about the 
level of the cells of Purkinje. In the white matter note the 
nuclei of the neuroglia cells. Everywhere note the blood- 
vessels both within the nervous tissue and the pia. 
Make a drawing of a portion of a lamina showing the 
distribution of the cells in the different layers and a high 
power drawing of each kind of cell. MEMORANDA The Nervous System. 
201 
35. Similar section. Weigert's myelin stain. 
Naked eye, ocular and low power. Note in each lamina 
the deeply stained core of white matter (why so deeply 
stained?), next a lighter layer, principally the granular 
layer (why stained more lightly?), and an external pale 
layer, most of the molecular layer (why pale?). Under low 
power note the arrangement of the medullated fibers in a 
single lamina. What is the arrangement? Are there any 
medullated fibers in the molecular layer? Where? 
Make a drawing of a single lamina showing the arrange- 
ment of the medullated fibers in each layer. 
36. Similar section. Cajal's silver stain. 
Naked eye, ocular and low power. Select a place where 
the stain is good and the section vertical. Identify the 
molecular, Purkinje and granular cortical layers and the 
white matter. Study the Purkinje cells, note the extent of 
their branching dendrites. Identify the basket fibers and 
study the pericellular baskets formed by their collaterals 
around the bodies of the Purkinje cells. What is their 
origin? Note the fibers in the granular layer and try to 
identify an axone of a Purkinje cell. 
Draw a small vertical portion of a lamina, sufficient to 
include one Purkinje cell and its basket. 
37. Similar section, showing the climbing fibers. Cajal's 
silver stain. 
Low power and high power. Examine the dendrites 
of the Purkinje cells for the appearances mentioned below. 
Study under high power the pale coarse dendrites with fine 
black fibers in apposition with them, the climbing fibers. 
Draw a few dendritic branches (high power) with their 
climbing fibers. 
38. Similar section, showing the mossy fibers. Cajal's 
silver stain. 
Low power and high power. Select portions of the 
granular layer which have a rather faintly mottled appear- 
ance. The small darker areas producing this appearance 
are the glomeruli. Examine (high power) and note the fi- 
bers,- with thickenings or excrescences as they pass through 
Qr end in the glomeruli. These are the mossy fibers. What 
structures are interlaced and terminate in the glomeruli? 
Draw (high power) some of the mossy fibers. 
39. Similar section. Golgi's chrome-silver impregnation. 
Low power. Find dendritic arborizations of Purkinje 
cells or a whole cell if possible, also look for granule cells MEMORANDA The Nervous System. 
203 
and neuroglia cells, the latter both in cortex and white 
matter. Look in the white matter for glia cells whose pro- 
cesses adhere to the walls of blood-vessels (the latter usu- 
ally stained brownish). Note the epithelial or spongio- 
blastic character of the glia cells whose processes extend 
through the molecular layer (fibers of Bergmann). 
High power. Note the excrescences ("gemmules") on 
the finer dendrites of the Purkinje cells and study further 
the above structures. 
Draw the above structures. 
40. Demonstration. Vertical section cut longitudinally 
through the laminae. Golgi's chrome-silver impregnation. 
Note the granule cells, their short dendrites and their 
axis-cylinder extending into the molecular layer and there 
bifurcating into two longitudinal fibers (the "parallel 
fibers"). Are the axones of the granule cells myelinated? 
Reason for answer? 
In the previous sections which are the fibers which 
terminate in the cerebellar cortex? From what cells do 
they arise? Of what paths are they a part and what is their 
functional significance? Which are the cells which send 
their axones out of the cerebellar cortex? Where do these 
axones end? Of what path are they a part and what is 
their functional significance? Which of the neurones 
studied are the association neurones of the cerebellar cortex 
and what are the possible functional connections which they 
may make? What light is thrown upon cerebellar function 
by the nature of the cerebellar connections and the cortical 
integrating mechanisms? Do the nature of the cerebellar 
connections and the structure of the cortex favor or con- 
tradict localization of function in it? What points require 
further investigation? 
41. Vertical section of an infant's cerebellar cortex. 
Nissl's or Weigert's stain. 
Note the presence of an external granular layer in the 
outer part of the molecular layer. What embryological 
significance has this? What is its significance as to the 
development of cerebellar functions? 
42. Transverse section of an infant's rhombencephalon 
through the isthmus and emergence of the trochlear nerve. 
Weigert's myelin stain. 
Naked eye, ocular and low power. Note the general 
shape of the isthmus. What is the trigonum lemnisci? 
Why so called? Note the small size of the fourth ventricle, MEMORANDA The Nervous System. 
205 
now passing into the iter. Distinguish the roof or superior 
medullary velum, the tegmentum and pons. Compare with 
a brain, brain model or illustrations of the brain. Note the 
decussation of the root fibers of nerve IV in the superior 
medullar velum and their emergence. What do they inner- 
vate? Note the various structures in the tegmentum. Has 
the medial lemniscus changed its position? The lateral 
lemniscus? In what respect? Note the nucleus of the 
lateral lemniscus. Note the beginning decussation (com- 
missure of Wernekinck) of the superior cerebellar peduncle 
or brachium conjunctivum. Identify the medial longitud- 
inal fasciculus (what fibers compose it here?), the central 
tegmental tract and the mesencephalic root of the trigemi- 
nus. Try to locate (high power) its nucleus, also the locus 
caeruleus and the positions of the rubro-spinal and lateral 
spino-thalamic (and spino-tectal) tracts. In some sections 
superficial fibers may be seen passing around outside the 
medial lemniscus. These may be the ventral spino-cere- 
bellar fibers which loop back into the cerebellum outside 
the superior peduncle. Note the presence of small lightly 
stained bundles of fibers in the medial lemniscus. These 
are aberrant pyramidal fibers. What is their probable 
source and destination? Note the nuclei reticularis. 
In the pons distinguish the pontile nuclei and the trans- 
verse, longitudinal and perpendicular fibers of the pons. In 
the infant the pyramidal fibers alone are well stained. 
Why? In some sections fibers may be seen proceeding 
from pons to medial lemniscus. These are other aberrant 
pyramidal fibers. What is their source and destination? 
What are the connections and paths of the nuclei and 
tracts studied in this section? 
Draw as directed in 1. 
43. Similar section of adult isthmus. Weigert's myelin 
stain. 
Note the points mentioned in 42 and compare the 
myelinization of the various fibers in the pons with those 
in the infant. 
44. Similar section of the isthmus. Nissl's stain. 
Study the cell groups mentioned in 42. If a drawing 
is made, draw as described in 3. 
45. Similar section of the isthmus. Cajal's silver stain. 
Study the various points mentioned in 42, 43 and 44. 
Note the large rounded cells of the mesencephalic tri- 
geminal nucleus. MEMORANDA The Nervous System. 
207 
G. Mesencephalon (Colliculi or Corpora Quadrigemina, 
Tegmentum, a portion of the Pons and Basis Pedunculi 
or Crus). 
1. Transverse section of an infant's mesencephalon 
through the inferior colliculi (posterior corpora quadri- 
gemina). Weigert's myelin stain. 
Naked eye, ocular and low power. Note the general 
shape of the section, the external eminences of the inferior 
colliculi, the trigonum lemnisci and the cavity of the 
brain, the iter or aquaeductus Sylvii (or cerebri). Distin- 
guish the roof part or colliculi, the tegmentum and the pons. 
Compare with a brain, brain model or illustrations of the 
braim Note the inferior colliculus and distinguish the large 
oval gray mass, the nucleus of the colliculus, external to 
which, dorsally, is the cortex of the colliculus. Note the 
commissure of the colliculi. Note the lateral lemniscus 
fibers entering the nucleus of the colliculus. What are the 
principal connections of the inferior colliculi and their gen- 
eral functional significance? 
In the tegmentum note the medial lemniscus, the lateral 
spino-thalamic and spino-tectal or spino-collicular tracts, 
the decussation of the superior cerebellar peduncles, and try 
to locate the rubro-spinal tract. In some sections the super- 
ficial pes-lemniscus bundles (an aberrant pyramid tract) 
may be seen medial to the medial lemniscus. In the central 
gray note the root fibers of nerve IV in its outer portion, 
sometimes visible as they are leaving their nucleus. Iden- 
tify the nucleus of nerve IV, indented in the dorsal surface 
of the medial longitudinal fasciculus. Reconstruct the cen- 
tral course of nerve IV. Note the mesencephalic root of 
nerve V, always bordering the central gray. Try to identify 
its nucleus (large rounded cells) ; also the locus caeruleus 
and nucleus tegmenti dorsalis. The central tegmental tract 
is difficult to distinguish among the decussating fibers of 
the superior cerebellar peduncle* In the pons note that the 
pontile nuclei and transverse fibers have diminished and the 
longitudinal fibers (only the pyramidal fibers being stained 
in the infant, why?) are being massed together. In some 
sections the anterior foramen caecum may be present in the 
median line between pons and tegmentum and laterally to 
it the interpeduncular ganglion or nucleus. What are the 
connections, paths and functions of the above nuclei and 
tracts? 
Draw as directed in F. 1 (rhombencephalon). MEMORANDA The Nervous System. 
209 
2. Similar section of the adult mesencephalon. Weig- 
ert's myelin stain. 
Note the points mentioned in 1. Compare the myelini- 
zation of the fibers in the pons with those of the infant. 
3. Similar section of the mesencephalon. Nissl's stain. 
Study the cell groups mentioned in 1. If a drawing is 
made, draw as directed in F. 3 (rhombencephalon). 
4. Similar section of the mesencephalon. Cajal's silver 
stain. 
Study the various points mentioned in 1, 2 and 3. Note 
the large round cells of the mesencephalic trigeminal 
nucleus. 
5. Transverse section of an infant's mesencephalon 
through the superior colliculi (anterior corpora quadri- 
gemina) and emergence of the oculomotor nerve. Weigert's 
myelin stain. 
Naked eye, ocular and low power. Note the eminences 
of the superior colliculi and the crusta or pes pedunculi and 
interpeduncular space. In the higher levels note the two 
lateral prominences, the medial or internal geniculate 
bodies. Note the emergence of the oculomotor nerve. What 
does it innervate? Note the aquaeductus Sylvii. Compare 
with a brain, brain model or illustrations of the brain. 
Distinguish the roof or superior colliculi, the tegmentum 
and the basis pedunculi, the latter replacing the pons and 
consisting of the substantia nigra and the pes pedunculi 
(crusta). The tegmentum and basis pedunculi are some- 
times collectively called the crura cerebri. 
In the colliculi note the various layers and if possible 
distinguish the alternating gray and white layers (stratum 
cinereum, stratum opticum, stratum lemnisci and the deep 
white layer next to the central gray composed of efferent 
collicular fibers from the preceding layers). What are the 
afferent and efferent connections of the superior colliculi 
and what is its general functional significance? 
In the central gray note especially the nucleus of the 
oculomotor nerve. Distinguish the lateral large-celled, and, 
if possible, the medial portions. In the higher levels iden- 
tify the small-celled Edinger-Westphal nucleus, more dors- 
ally located. What is probably the functional difference 
between the large- and small-celled portions of the nucleus? 
What fibers probably terminate in this nucleus? What are 
their functional significances? Trace the course of the root 
fibers to the surface. Note the brachium of the inferior 
14 MEMORANDA The Nervous System. 
211 
colliculus. Why so called and what does it connect? Func- 
tional significance? Note the lateral spino-thalamic (and 
spino-tectal or spino-collicular) tract, here quite distinct. 
Functional significance? Has the medial lemniscus changed 
in shape or position? Note the large nucleus ruber. The 
emergence from it and decussation of the rubro-spinal tract 
(ventral tegmental decussation of Forel) has taken place in 
somewhat lower levels. Look for the decussation of the 
colliculo-bulbar and colliculo-spinal fibers (dorsal tegmental 
decussation of Meynert). It may take place in a somewhat 
lower level than the section. Are there any decussating 
fibers of the superior cerebellar peduncle present? What 
are the various probable connections of the nucleus ruber? 
Locate .the central tegmental tract in the gray reticular 
formation. Where does it terminate? Is its exact origin 
known? 
Note the substantia nigra. Why so called? Ventrally, 
note the mass of fibers known as the pes pedunculi. What 
fibers compose it? Origins? Terminations? Paths? Func- 
tional significance? Note that in the infant only the fibers 
of the middle portion of each pes is medullated. What 
fibers are these? What are the non-medullated fibers? 
(Compare section 6 below.) In many sections of the 
higher levels note the fibers from the pes passing into the 
lateral part of the substantia nigra, the deep (or lateral) 
pes-lemniscus fibers. What is the source and destination 
of these aberrant pyramidal fibers? Function? In some 
sections (not constant) fibers pass from the pes around 
its outer side to take a position medial to the medial fillet, 
the superficial (or medial) pes-lemniscus bundle. They are 
also aberrant pyramidal fibers. Source? Destination? 
Function? 
If the medial geniculate body be present, note the 
lateral lemniscus fibers entering it. 
What are the connections, paths and functional signi- 
ficance of the nuclei and tracts in this section? 
Draw as directed in F. 1 (rhombencephalon). 
6. Similar section of the adult mesencephalon. Weig- 
ert's myelin stain. 
Observe the points mentioned in 5. Compare especially 
the myelinization of the fibers of the pes with those in 5. 
What general method does this comparison illustrate? 
7. Similar section of the mesencephalon. Nissl's stain. 
Study the cell groups mentioned in 5. If a drawing is 
made, draw as directed in F. 3 (rhombencephalon). MEMORANDA The Nervous System. 
213 
8. Similar section of the mesencephalon. Cajal's silver 
stain. 
Study the various points mentioned in 5, 6 and 7. Study 
especially the nucleus of the oculomotor nerve. 
H. Prosencephalon (Diencephalon [Epithalamus, Thalamus 
and Hypothalamus] and Telencephalon [Rhinenceph- 
alon, Corpora Striata and Pallium]). 
1. Transverse section through the junction of midbrain 
and forebrain. Weigert's myelin stain. 
Naked eye, ocular and low power. Note the dorsal 
eminences of the superior colliculi still present, between 
which may be, if not detached in preparation, the pineal 
body. Laterally is the overhanging pulvinar of thalamus 
which in turn passes laterally into the cerebral hemisphere. 
Ventro-laterally is the protruding lateral or external genic- 
ulate body, more medially the pes and, between the two 
pedes, the interpeduncular or posterior perforated (why so 
called?) space. In the latter the root fibers of the oculo- 
motor nerve may be seen emerging. Compare with a brain, 
brain model or illustrations of the brain.. ' 
Distinguish in the section the lateral portions belonging 
to the telencephalon, the portions belonging to the dien- 
cephalon (pulvinar, medial and lateral geniculate bodies 
and pineal body) and the parts belonging to the mesen- 
cephalon (superior colliculi, tegmentum and basis pedunculi, 
the latter composed of' substantia nigra and pes). Note 
the aquaeductus Sylvii. 
Midbrain. Note the central gray and within its ven- 
tral portion the oculomotor nuclei. Identify the Edinger- 
Westphal nucleus, if present. Trace the root fibers of the 
oculomotor nerve to their exit. Note the colliculi and their 
commissure. In higher sections the posterior commissure 
may be present. In the tegmentum note the large nucleus 
ruber with fibers within and on its medial aspect. What 
are these fibers, in part at least? Note the nuclei reticularis 
and fiber bundles in tihe gray reticular formation which is 
still present. Note the medial lemniscus, now showing 
signs of dispersion. Dorsal to it is the lateral spino-thala- 
mic tract. Note that the medial longitudinal fasciculus is 
diminished. Laterally to it is the nucleus of the posterior 
commissure which, with other larger cells of a motor ap- 
pearance (in Nissl preparations) in the reticular formation 
(interstitial nucleus), is believed to give rise to descending 
fibers from the midbrain forming part of the medial longi- 
tudinal fasciculus. Note the substantia nigra. It may con- MEMORANDA The Nervous System. 
215 
tain aberrant pyramidal bundles (subthalamic bundle and 
deep pes-lemniscus bundle). The large mass of fibers 
forming the pes is unaltered. 
Thalamus. Identify the medial geniculate body and 
note the fibers accumulating on its lateral aspect. Where 
do they probably go? What fibers does this body receive? 
General functional significance? Note the lateral geniculate 
body. What are the fibers on its ventral aspect? Their 
origin? Dorsally may be seen the field of Wernicke com- 
posed of fibers curving dorsally towards the pulvinar (col- 
laterals of the optic tract?), crossed by fibers of the thalamic 
radiation. Functional significance of the lateral geniculate 
body? Note the large pulvinar and the fibers radiating 
from it (part of the thalamic radiation), traversing the 
retrolenticular portion of the internal capsule and entering 
the corona radiata of the pallium. What three great sen- 
sory paths undergo relays in this part of the brain? What 
is the significance of these thalamic relays? 
Draw as directed in section F. 1 (rhombencephalon). 
2. If No. 1 is a section of the infant's brain, study a 
similar section of the adult brain. Weigert's myelin stain, 
and compare with 1. 
3. Similar transverse section. Nissl's stain. 
Study the cell groups mentioned in 1. If a drawing is 
made, draw as directed in F. 3 (rhombencephalon). 
4. Transverse section of the diencephalon through the 
optic chiasma. Weigert's myelin stain. 
Naked eye, ocular and low power. Note the optic 
chiasma and tuber cinereum on the ventral aspect. Note 
the third ventricle and (usually torn away) its roof, the 
tela chorioidea. In more frontal sections the sulcus hypo- 
thalamicus may be seen on the inner, ventricular wall of the 
diencephalon. Note the optic tract passing to about the 
location of the lateral geniculate body in the preceding 
level. Compare with a brain, brain model or illustrations 
of the brain. 
Epithalamus. Note the 'habenula and its nucleus and, 
if the section is at the right level, the habenular commissure. 
Note the beginning of'the fasciculus retroflexus of Meynert. 
Where does it originate? Where terminate? Of what path 
is it a part? Note the taenia thalami and near it the bundle 
of fibers known as the stria medullaris, terminating partly 
in the nucleus habenulae. Note the stalk of the pineal body. 
Thalamus. Note the lateral and ventro-lateral nuclei, 
more medially the arcuate nucleus and the median center of MEMORANDA The Nervous System. 
217 
Luys. Note that the medial lemniscus has disappeared in 
the ventrolateral nucleus. Tn higher sections the medial 
thalamic nuclei are separated from the more lateral by the 
medial medullary lamina (of medullated nerve fibers). 
What is the general difference between the medial and 
lateral nuclei in respect to their connections with the as- 
cending tracts and cortical connections? What is its prob- 
able functional significance as regards sensation? From 
the lateral portions of the thalamus note the fibers of the 
thalamic radiations passing dorso-laterally to the lateral 
border of the thalamus, forming there the lateral medullary 
lamina and thence passing obliquely across the internal 
capsule into the corona radiata. What are the connections 
of these fibers? Functional significance? Note the small 
bundle of fibers at the junction of caudate nucleus and 
thalamus, the stria cornea (stria semicircularis, from pri- 
mary olfactory cortex to nucleus amygdalae). In the ven- 
tral part of the thalamus note the tegmental area H of Forel 
which replaces the nucleus ruber (present in some of the 
sections). Laterally from this proceed the fibers of the 
tegmental radiation (field Hl of Forel, representing con- 
nections of nucleus ruber with pallium?). Ventrally is the 
gray zone incerta and ventrally to this a bundle of fibers, 
the lenticular bundle (field H2) of Forel, a part of the 
ansa lenticularis system. These latter fibers can be seen 
passing through (fibrse perforantes) the adjacent lenticulo- 
thalamic segment of the internal capsule to the globus palli- 
dus (see below) from which they originate. They pass 
to the corpus subthalamicum of Luys (see below), to the 
tuber cinereum, also probably to the nucleus ruber and 
possibly to the substantia nigra. Ventrally to this bundle 
note the corpus subthalamicum of Luys. 
Hypothalamus. Note the tuber cinereum and the mam- 
millary bodies. In the lateral portion of the latter note the 
termination of the descending anterior pillar of the fornix 
(connections?). From the medial part of the mammillary 
body note the fasciculus mammillaris princeps, a part of 
which higher forms the mammillo-thalamic bundle of Vicq 
d'Azyr. What are the paths of which these connections 
are a part? 
Telencephalon: Corpus striatum. Note, at the dorso- 
lateral border of the thalamus, the tail of the caudate 
nucleus. Externally to the internal capsule (pes) note the 
lenticular nucleus. Distinguish its lateral part, with com- 
paratively few medullated fibers, the putamen, and its 
medial part, the globus pallidus, with radiating medullated MEMORANDA The Nervous System. 
219 
fibers. Why are these various names appropriate? Note 
that the globus pallidus is both subdivided and separated 
from the putamen by laminae of medullated fibers (probably 
principally fibers of passage). 
Internal capsule. Note that a considerable portion of 
the pes is now between the thalamus and lenticular nucleus, 
constituting the posterior or lenticulo-thalamic portion of 
the internal capsule. Note also that the fibers of the dorsal 
part of the capsule are, in company with the fibers of the 
thalamic radiation, passing into the corona radiata of the 
pallium. Correlate the portions of the internal capsule seen 
in these sections with the various portions of the capsule 
seen in horizontal (frontal) sections. 
Draw as directed in F. 1 (rhombencephalon). 
5. If the preceding is a section of the infant's brain, 
study a similar section of the adult brain, Weigert's myelin 
stain, and compare with 4. 
6. Similar section. Nissl's stain. 
On comparing with the cell groups as seen in myelin- 
stained sections it will be observed that the various thalamic 
nuclei do not each always have their own peculiar type of 
cell. Most nuclei have small cells, presumably many with 
axones confined to the thalamus or to the nucleus itself. 
Some nuclei have only small cells, other nuclei have in 
addition other larger types of cells more peculiar to them. 
The ventro-lateral nuclei have scattered very large cells, 
possibly those cells sending fibers to the primary sensory 
cortical areas. There are no cells of the "premotor" type 
in the thalamus proper. If a drawing is made, draw as 
directed in F.-3 (rhombencephalon). 
7. Similar section. Cajal's silver stain. 
Note, as far as possible, the features observed in 4, 5 
and 6. 
8. Transverse section of the thalamus, internal capsule 
and corpus striatum through the anterior cerebral commis- 
sure. Weigert's myelin stain. 
Naked eye, ocular and low power. Distinguish the 
thalamus, corpus striatum and internal capsule. 
Thalamus. Note the medial nucleus separated by the 
medial medullary lamina from the lateral nucleus. Note 
the mammillo-thalamic bundle beginning to disperse in the 
medial nucleus and the fibers connecting the medial nucleus 
with the nucleus caudatus and globus pallidus (part of the 
ansa lenticularis in a broad sense; here forming a part MEMORANDA The Nervous System. 
221 
of the inferior thalamic peduncle). Note the fibers passing 
from the lateral thalamic nucleus, forming the lateral med- 
ullary lamina and passing through the internal capsule into 
the corona radiata. 
Corpus striatum. Note the globus pallidus and puta- 
men. Note the anterior commissure connecting the corpora 
striata. Dorsal to it note the descending anterior pillars 
of the fornix. Note the internal capsule, its dorsal part 
continuous with the white matter of the pallium. This 
section is near its genicular portion. What fibers in it are 
here passing into the corona radiata? Origin? Destination? 
Path? Function? Effects of injury to this part of the 
internal capsule? 
Draw as directed in F. 1 (rhombencephalon). 
9. If the preceding is a section of the infant's brain, 
study a similar section of the adult brain, Weigert's myelin 
stain, and compare with 8. 
10. Similar section. Nissl's stain. 
Study the cell groups of the thalamus and corpus 
striatum. Note in the latter the large cells, principally 
found only in the globus pallidus. What is their probable 
significance? If a drawing is made, draw as directed in 
F. 3 (rhombencephalon). 
11. Similar section. Cajal's silver stain. 
Note, as far as possible, the features observed in 8, 9 
and 10. 
12. Transverse section of the olfactory bulb. Weigert's 
myelin stain. 
Compare with illustrations of preparations by Golgi's 
chrome-silver method. 
Distinguish: (a) The external layer of olfactory fibers 
(from what cells?); (&) the glomerular layer (constituents 
of the glomeruli?) ; (c) the molecular or external plexiform 
layer (dendrites, collaterals and axones from mitral and 
granule cells) ; (d) the mitral layer (bodies of the mitral 
cells) ; (e) internal plexiform layer; (/) central white sub- 
stance (axones of mitral and other cells, secondary ol- 
factory tract, also some fibers to the bulb), mingled with 
granule cells. 
Draw, showing the above layers. 
13. Demonstrations, as far as possible, of above and also 
of the olfactory cells of the mucous membrane. Golgi's 
chrome-silver impregnation. MEMORANDA The Nervous System. 
223 
14. Vertical section of the area calcarina (visual area) 
of the cortex pallii. Nissl's stain. 
Ocular and low power. Distinguish the following 
layers: (1) The zonal or molecular layer, with very few 
nerve cells; (2) the external granular layer (small pyramidal 
cells) ; (3) the pyramidal layer (medium and large pyra- 
midal cells) ; (4) the internal granular layer,-here subdivided 
into the external sublayer of large granule cells and the 
internal sublayer of small granule cells; (5) ganglionic layer 
(internal layer of pyramidal cells) and (6) the multiform 
layer of triangular and fusiform cells. How does the above 
differ from the typical cortex? 
Draw a thin vertical strip indicating the above cell 
layers (cytoarchitecture). 
Study and make a high power drawing of each of the 
different types of cells showing shape, nucleus and especially 
the arrangement, etc., of the chromophilic bodies. 
15. Similar section. Weigert's myelin stain. 
Naked eye, ocular and low power. Note the three gen- 
eral categories of fibers, (a) tangential fibers running 
parallel to the surface of the brain. These may be super- 
ficial or deep. (&) fibers passing obliquely and (c) radial 
fibers, arranged in bundles. In certain layers the tangential 
and oblique fibers, especially the former, may be especially 
numerous giving rise to the various lines or strise. 
Distinguish the following layers: (a) The tangential 
layer of superficial tangential fibers, corresponding to (1) 
in 14; (&) a layer with few medullated fibers (dysfibrosa) ; 
(c) the suprastriate layer (separated from (&) often by the 
Kaes-Bechterew line or stria) ; (d) external line or stria of 
Baillarger, here the line of Gennari; (^) infrastriate layers. 
(Where there is also an internal line of Baillarger, this and 
an interstriate layer are added.) In general, layers (a), (&) 
and part of (c) are also termed the supraradiary layers and 
the remaining layers the radiary layers, according to the 
absence or presence of the radiations. 
Note especially in this section the clearly marked limits 
of the line of Gennari. What area is thus distinguished by 
the presence of.this line? Note also where the radiations 
end and any sublayers of the zonal layer. 
Draw a thin vertical strip of the cortex showing the 
arrangement of the above myelinated fibers (myeloarchi- 
tecture). 
16. Similar section. Cajal's silver stain. 
Study the cells and fibers composing the various layers. MEMORANDA The Nervous System. 
225 
17. Demonstrations of Golgi preparations showing the 
shapes and processes of the various types of cortical cells 
and especially the course of their axones. Note the pre- 
vailing type, the pyramidal cells with long apical and 
shorter basal dendrites, the former usually directed towards 
the periphery. Note the axones, usually directed towards 
and into the white matter. Note, if present, inverted cells 
in which the opposite obtains and also pyramidal cells with 
axones which turn upward toward the periphery. Note the 
collaterals In the granule or stellate cells the dendrites 
pass off equally in all directions, the axones may pass into 
the white matter or they may be short axones, often di- 
rected upward. Other modifications of these types are 
present. The polymorphous-cells of the sixth layer usually 
send their axones into the white matter. Fibers from else- 
where (what sources?) terminate in all layers and especially 
in the line of Gennari. What is the probable origin of some, 
at least, of the latter? 
Correlate this picture with that obtained by the myelin 
stain. What are the fibers of the radiations and the fibers 
of the striae? 
18. Vertical section of the precentral (motor) cortex 
pallii. Nissl's stain. 
Ocular and low power. Distinguish, as far as possible, 
the same cell layers as in 14. Note, however, that the 
internal granular layer is practically indistinguishable. 
Note also the presence of the giant cells of Betz in the 
ganglionic layer. 
Make a drawing of a thin vertical strip of the cortex, 
indicating the arrangement of the cells, their sizes, etc. 
Make a (high power) drawing of a cell of Betz. What 
type of cell does it resemble with respect to its chromo- 
philic bodies? What are the destinations of the axones of 
these cells? About what percentage of all the cells in the 
section are cells of Betz? What is probably the general 
nature of the connections of the other cells? 
19. Similar section. Weigert's myelin stain. 
Distinguish the various fibers as in 15. Note the great 
abundance of medullated fibers, the great thickness of the 
cortex and the absence of striae. 
Draw a thin vertical strip of the cortex showing the fiber 
arrangement. 
20. Similar section. Cajal's silver stain. 
Study the cells and fibers of the various layers. 
15 MEMORANDA The Nervous System. 
227 
21. Demonstration of Golgi preparations as in 17. 
Correlate the various pictures obtained from different 
preparations. 
Construct a general conception of the cortical connec- 
tions: The afferent fibers from other parts of the brain 
(sources and functional significance?), fibers to (and from) 
other parts of the cortex (functional significance?) and 
fibers to other parts of the brain (functional significance?). MEMORANDA CHAPTER XVIII. 
ORGANS OF SPECIAL SENSE. 
1. Eye of sheep. Gross preparation. 
With razor or sharp knife bisect eye, being sure that 
section passes through optic nerve. Examine carefully 
under water. Identify: (1) Anterior chamber filled with 
aqueous humor. (2) Lens. (3) Posterior chamber filled 
with vitreous (glassy) humor. The vitreous humor is sur- 
rounded by a delicate hyaloid membrane attached to the 
retina and to inner surface of lens. (4) Sclera and cornea 
forming the outer coat. How does the latter differ in the 
gross preparation? (5) Chorioid, ciliary body and iris. 
What is the color of the chorioid? Separate chorioid from 
sclera and note the loose lamina fusca. In ciliary body 
identify ciliary folds and ciliary processes, and note delicate 
suspensory ligament which attaches ciliary body to lens. 
(6) Retina. What is its color? Note that the optic part 
of the retina is bounded by a ragged line, the ora serrata, 
beyond which it is continued as the ciliary and iridic por- 
tion. Note the optic disc and its central excavation. How 
is the disc formed? What is its physiological significance? 
What is the blind spot? Fovea centralis? Significance? 
Is part of the optic nerve present? 
Make drawing showing all parts seen. 
2. Section through eye. Microscopic study. 
Under ocular and low power identify again the following 
structures: Anterior and posterior chambers, lens, cornea, 
sclera, chorioid, ciliary body (ciliary folds and processes), 
retina (optic, ciliary and iridic portions), optic disc, optic 
nerve. Draw. 
Under high power study and draw strip through the 
three coats of the eye. 
Make out the following: 
(a) Sclera, noting the dense fibrous tissue of which it 
is composed. What is the direction of the 
fibers? Distribution of cells? Where the optic 
nerve enters the sclera is broken up forming 
the lamina cribosa. Note pigmented layer of 
flat cells (lamina fusca) separating sclera from 
chorioid. 
229 MEMORANDA Organs of Special Sense. 
231 
(&) Chorioid. Make out the four layers (lamina 
supra-chorioidea, Haller's layer, capillary layer, 
vitreous membrane). What is the structure of 
each? Is pigment found? Where most abun- 
dant? Note the blood-vessels in Haller's layer. 
What is their arrangement? In capillary layer 
note the dense net work of capillaries. Where 
are they most abundant? The seemingly struc- 
tureless vitreous membrane separates the 
chorioid from the retina. 
(c) Retina. Make out: (1) Layer of pigmented epi- 
thelium ; (2) neuro-epithelial layer consisting 
of layer of rods and cones, outer limiting layer 
and outer nuclear layer; (3) ganglionic layer 
consisting of outer molecular layer, inner nu- 
clear layer, inner molecular layer, layer of nerve 
cells, layer of nerve fibers and inner limiting 
membrane. Study carefully structure of each 
layer. How many cell layers in retina? Rela- 
tive number of rod and cone cells, bipolar cells 
and large nerve cells? Significance? Recon- 
struct the cellular elements of the retina show- 
ing the relation to each other. 
(J) Cornea. Study and draw. Make out anterior 
epithelium, anterior elastic membrane (mem- 
brane of Bowman), substantia propria, posterior 
elastic membrane (membrane of Descemet), 
posterior endothelium (endothelium of Desce- 
met). Which is the chief epithelial layer? 
What type of epithelium? Can you distinguish 
conjunctival from corneal epithelium? Is the 
cornea vascular? 
(f) Iris and ciliary body. What coats contribute to 
their formation? Note pigmented epithelium 
lining the inner surface of the ciliary folds and 
ciliary processes. This is the ciliary part of the 
retina. Make out ciliary muscle. What type 
of muscle? Disposition of fibers? The ciliary 
body is attached to the sclero-corneal junction 
by an elastic ligament (ligamentum pectinatum) 
in which endothelial spaces (spaces of Fontana) 
may be seen. Draw. In iris note again the 
inner pigmented layer formed by iridical part 
of retina. Outside of this layer study structure 
of anterior epithelium, stroma and vitreous MEMORANDA Organs of Special Sense. 
233 
membrane. Is smooth muscle found? Where? 
Draw strip through iris. 
(/) Study carefully structure of sclero-corneal junc- 
tion. Note canal of Schlemm and attachment 
of ligamentum pectinatum. Significance of 
canal of Schlemm and spaces of Fontana? 
Draw. 
(g) Study optic nerve. Note the nerve fibers, the 
dural, pial and arachnoid sheaths, the sub- 
arachnoid space. Are the nerve fibers medul- 
lated? Do they possess a neurolemma? Note 
that where the nerve passes through sclera the 
connective tissue of the latter is broken, forming 
a lattice work (the lamina cribrosa). Can you 
find central blood-vessel? Study the optic disc. 
Of what does it consist? Are the fibers mye- 
linated? Are rods and cones present in region 
of disc? Draw. 
3. Study demonstration preparation through fovea cen- 
tralis. How does it differ from other portions of the retina? 
4. Study demonstration of retina with injected blood- 
vessels. 
5. Study Golgi demonstration of retina, showing relation 
of various cells. 
6. Section through cochlea. 
Study with ocular and low power. Identify the central 
bony axis (modiolus), the bony spiral lamina and the canal 
of the cochlea. In latter note Reissner's membrane and the 
basilar membrane dividing canal into three parts, an upper 
(scala vestibuli), a lower (scala tympani) and a middle 
(scala media, cochlear duct). In cochlear duct note organ 
of Corti resting on basilar lamina, spiral ligament, spiral 
crista, spiral prominence, spiral limbus and tectorial mem- 
brane. Note spiral ganglion in bony lamina sending out 
peripheral processes through bony sulcus to organ of Corti. 
Low power drawing indicating parts seen. 
Under high power study carefully and draw organ of 
Corti. Identify the following kinds of epithelial cells and 
study their shape, cytoplasmic structure, position of nucleus 
and distribution in organ of Corti,-pillar cells, auditory 
(hair) cells, Deiters's cells, Hensen's cells. Distinguish be- 
tween inner and outer hair cells? Function of the var- 
ious cells? What is meant by Corti's tunnel? Study struc- MEMORANDA Organs of Special Sense. 
235 
ture of tectorial membrane. Where is it attached? What 
is its shape? In membrane note the fine radial striations 
and absence of nuclei. Function of tectorial membrane? 
Study spiral ganglion. What type of neurones compose it? 
Trace peripheral fibers from ganglion to hair cells. Where 
do central fibers go? Of what cranial nerve are they a 
part? Study carefully the basilar lamina, the spiral limbus 
and spiral ligament, noting their structure and relation to 
organ of Corti. 
7. Study Golgi demonstration showing termination of 
nerve fibers in organ of Corti. 
8. Section through crista of semicircular canal. 
Study under high power. Identify sustentacular cells, 
hair cells, otolithic membrane. Note that the epithelium 
rests on a connective tissue stroma which is attached to 
the bony capsule. Nerve fibers run through stroma to 
termination among hair cells. 
9. Study demonstrations of macula acustica of utricle 
and saccule and compare with crista. 
10. Section through olfactory mucosa. 
Under low power identify the neuro-epithelial coat and 
the underlying stroma of fibro-elastic tissue. Are glands 
present? What type? Under high power study the olfac- 
tory epithelium. Identify the sustentacular and olfactory 
cells, and the layer of flattened basal cells. Compare sus- 
tentacular and olfactory cells with regard to position in 
mucosa, shape of nucleus, character of cytoplasm and cell 
processes. What is there unique about the olfactory cells? 
From what structure are they derived? What forms the 
olfactory nerve? Draw strip through olfactory epithelium. 
11. Study Golgi demonstration showing the olfactory 
cells. 
12. Section through taste bud. 
Under low power identify taste bud and gustatory pore. 
What tissue surrounds the taste bud? On what does it 
rest? 
Under high power study shape and structure of (a) sus- 
tentacular cell. (&) Gustatory cell. Compare with similar 
cells of olfactory mucosa. Draw. 
13. Study Golgi demonstration showing nerve termina- 
tions in taste bud.