Kinetic studies on glial, Schwann and capsular cells labelled with [3H] thymidine in cerebrospinal tissue of young mice.

Neuroglia, capsular and Schwann cell renewal and turnover in the cerebellum, the spinal cord and spinal ganglia have been evaluated in 2-months-old mice. The animals received intraperitoneal injections of [3H] thymidine at 8 hr intervals starting on the 28th day of postnatal life for a period of 30 days and were killed 1 hr after the last injection. Substantial numbers of labelled neuroglial cells but no labelled neurons were observed. Oligodendrocytes of the cerebellum and the spinal cord showed higher labelling indices (19.8% and 18.0%, respectively) than astrocytes (10.0%) and Bergmann's supporting cells (7.2%). The labelling indices of capsular cells in the spinal ganglia and Schwann cells in the spinal roots were 35.8% and 25.8%, respectively. The experiments failed to provide evidence for matrix cell layers in the cerebellum, the spinal cord and spinal ganglia. It may be concluded therefore that glial and Schwann cells in these parts of the nervous system proliferate in situ.