SCHWANN CELL PROLIFERATION IN DEVELOPING MOUSE SCIATIC NERVE

Abstract

Twenty-eight mice were injected with thymidine-3H, 4 uc/g, 48 hr. after birth, and were killed serially over the next 4 days. Sections in 1-u glycol methacrylate were studied. For the cell cycle following injection, the generation time was approximately 24 hr. as determined by grain-count halving data; the duration of synthesis phase was 8 hr. as determined from a curve constructed from the per cent of mitotic figures containing label; and the labeling index was 9% at 2 hr. after injection. With these estimates, the per cent of Schwann cells proliferating was calculated to be 27%. Roughly 25% of dividing cells appeared to cease division during the cell cycle under study. The relationship of these findings to other events during maturation of nerve is discussed.