January 9, 1962

Or. R.L. Sidman
Laboratory for Cellular Neuropathology

Hervard Medical School
Boston, Massachusetts

Dear Or. Sidman:

May | ask you for reprints of your recent papers on audioradiographic
studies of neural! development, which would be very much appreclated.

The neuron Is often cited as a cell which has a very long life
history in the absence of mitosis and putatively of DNA turnover. |
not been able to find very extensive experimental studies bearing on
this point = can you site them, or can you Indicate from your own experiences
the lower limit for the half life of neuronal DNA In an adult animal?

have

Yours sincerely,’

Joshua Lederberg
Professor of Genetics

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7M COnerurd,