Observations on proliferating sheath cells in the regenerating nerves of lizard.

The proliferation of sheath cells (Schwann and endoneurium) of growing nerves has been studied by autoradiography after 3H-thymidine administration to lizards (Anolis carolinensis and Lampropholis delicata) with regenerating tails. Schwann cells of regenerating nerves derive from the multiplication of resident cells within the growing nerves, but labelled Schwann cells derived from the regenerative blastema also appear to ensheath the new axons. Endoneurium cells of growing nerves derive from the blastema around the nerves more than from dividing and migrating cells of the original endoneurium. After 6-20 days post-injection the number of labelled sheath cells in the older proximal regenerated nerves increased due to local division and migration. In the proximal spinal ganglia which innervate the regenerating tail some satellite cells, but not neurons, took up 3H-thymidine and multiplied.