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also myeline, "soft material found in nerve tissues," 1867, from German Myelin (1854), from Greek myelos "marrow; the brain, innermost part," of unknown origin.
myelin my·e·lin (mī'ə-lĭn) or my·e·line (-lĭn, -lēn')
A white fatty material composed chiefly of alternating layers of lipids and lipoproteins that encloses the axons of myelinated nerve fibers.
Droplets of lipid formed during autolysis and postmortem decomposition.
white, insulating sheath composed of fatty materials, protein, and water on the axon of many nerve fibres. The myelin sheath is deposited by Schwann cells in layers surrounding the nerve fibres of the central and peripheral nervous systems of many organisms. The sheath is interrupted at intervals by gaps called nodes of Ranvier; this structure speeds nerve conduction, as impulses jump from node to node in a process known as saltatory conduction.