Proliferation of Schwann cells in demyelinated rat sciatic nerve.

Experimental demyelination was induced by intraneural injection of anti-galactocerebroside serum into the sciatic nerves of rats. Schwann cells undergoing mitotic division were observed between days 3 to 9 after the injection and demyelinated segments were still associated with macrophages. Dividing Schwann cells were often present in association with both unmyelinated and myelinated fibers. Whether or not, daughter Schwann cells migrate along the same fiber towards neighboring demyelinated segments remains unclear. When Schwann cells attached to axon membranes of demyelinated segments were studied at later time points, they were present in clusters randomly at various regions of the segments. There was no proximo-distal gradient for the wave of Schwann cell proliferation. Mean Schwann cell internuclear distances were around 40-50 microns at the earliest time of remyelination. Schwann cell redistribution and remyelination progressed regardless of the length of demyelinated segments.