Remyelination of nerve fibers in the transected frog sciatic nerve.

This project tests an important aspect of the cellular events controlling the processes of recovery of function and remyelination that follow demyelination in the peripheral nervous system. Frog sciatic nerves have been shown to survive and remain functional for up to 10 days following transection. We have utilized this property in order to dissociate the recovery process from possible control by the neuronal soma. Xenopus sciatic nerves were demyelinated in one branch by an intraneural injection of lysolecithin. The nerve was cut proximally to the injection site either immediately before, or several days after the lysolecithin injection. Recovery of function and remyelination were then followed by electrophysiological, optical, and ultrastructural techniques applied both to whole branches and single fibers. Controls included the cut but uninjected branch, and injected but uncut nerves. The progression of events during both demyelination and recovery in cut axons was indistinguishable from that in uncut fibers. This suggests that this process may be under local control and can be initiated and carried out in the absence of constant communication with the nerve cell body.