The Probert Encyclopaedia of Medicine

MYELIN SHEATH

The myelin sheath is a coat of white, fatty tissue (myelin) which covers the axons of nerves of the peripheral nervous system. The white, myelinated fibres of the nerve bundles within the brain and spine account for the white matter found there. The grey matter also there is due to the inner structures of the nerve cell bodies. The myelin sheath is, in turn, covered by a membrane called the neurolemma (or the nucleated membrane). The myelin sheath serves to insulate the axon, thereby improving signal transmission to the nerve. When the myelin sheath is lost or damaged, signal loss occurs and this manifests itself in symptoms such as those encountered in the disease multiple sclerosis.
Research Myelin Sheath