Myelin

[maiәli(:)n]

Definition

(noun.) a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers.

Edited by Astor--From WordNet

Definition

(n.) A soft white substance constituting the medullary sheats of nerve fibers, and composed mainly of cholesterin, lecithin, cerebrin, albumin, and some fat.

(n.) One of a group of phosphorized principles occurring in nerve tissue, both in the brain and nerve fibers.

Edited by Ingram