Schwann cells divide in a demyelinating lesion of the central nervous system.

A demyelinating lesion was induced in the rat central nervous system (CNS) by the microinjection of lysophosphatidylcholine into the spinal cord. Animals were given a single dose of tritiated thymidine 6-72 h before perfusion fixation. Correlative light microscope autoradiography and electron microscopy revealed many labeled Schwann cell nuclei that were associated with demyelinated axons in 1-3 week lesions. Myelinating Schwann cells were rarely labeled. The results indicate that Schwann cells proliferate in the CNS. They appear to divide on contact with demyelinated axons and to stop dividing when they form myelin.