Fig. 8.

Axons regulate Schwann cell proliferation during development. Schwann cell proliferation in the lumbar ventral root is greatest at E4–E5, followed by a gradual reduction throughout the remainder of incubation (A). Although NMDA treatment reduces Schwann cell proliferation at E10, an increase in proliferation at E16 is evident by 24 hr after NMDA treatment (*p < 0.05) (B). The absence of BrdU (red) and TUNEL (green) double labeling at E10.5 indicates that mitotic Schwann cells do not undergo cell death after NMDA treatment at E10 (C). In A, each point represents the mean ± SEM for three to six embryos, and inB, numbers in barsindicate sample size.