Long lives for homozygous trembler mutant mice despite virtual absence of peripheral nerve myelin.

Nervous system functions are dependent on point-to-point communication of signals along neuronal axons, and axonal insulation by myelin is thought to speed such conduction. Loss of previously formed myelin or lack of myelin formation can have serious, even fatal, consequences. Mice homozygous for the trembler mutation make virtually no peripheral nervous system myelin, yet have long and functional lives. This result calls into question the view that peripheral nervous system myelin plays a vital role, at least in this species.