Mitotic Schwann cells in normal mature spinal roots.

Some rare mitotic Schwann cells (one in about a thousand) were found in normal mature spinal roots of adult lizards. Mitotic cells retained their relationships with unmyelinated axons, a finding consistent with the hypothesis that the stimulation of Schwann cell proliferation requires direct contact between axons and Schwann cells. The observation presented in this paper shows that Schwann cells and the satellite cells of sensory and autonomic ganglia behave in the same way also with regard to their mitotic activity.