myelin sheath

noun

Anatomy.

1. a wrapping of myelin around certain nerve axons, serving as an electrical insulator that speeds nerve impulses to muscles and other effectors.

Word History and Origins

Origin of myelin sheath¹

First recorded in 1895–1900

Example Sentences

Their findings show that the immune system begins attacking the brain's protective myelin sheath -- the fatty covering that insulates nerve fibers -- much earlier than scientists once believed.

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In MS, the immune system mistakenly attacks the myelin sheath, a protective layer that insulates nerve fibers.

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However, EBV infection has been linked to several diseases, including MS: an incurable, chronic autoimmune disease that causes the body's immune system to attack the myelin sheath of neurons in the brain and nervous system.

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These useful cells in the brain, called oligodendrocytes, are responsible for producing myelin sheaths that wrap around cable-like parts of nerve cells called axons, much like the plastic insulation around a wire.

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For example, in vertebrates, the researchers found genes critical for the formation of myelin sheaths around nerve cells, which are essential for fast nerve signal transmission.

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