myelin

American  

[mahy-uh-lin] / ˈmaɪ ə lɪn /

Also myeline

noun

Biology.

1. a soft, white, fatty material in the membrane of Schwann cells and certain neuroglial cells: the substance of the myelin sheath.

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myelin British  

/ ˈmaɪɪˌliːn, ˈmaɪɪlɪn /

noun

1. a white tissue forming an insulating sheath ( myelin sheath ) around certain nerve fibres. Damage to the myelin sheath causes neurological disease, as in multiple sclerosis

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myelin Scientific  

/ mī′ə-lĭn /

1. A whitish, fatty substance that forms a sheath around many vertebrate nerve fibers. Myelin insulates the nerves and permits the rapid transmission of nerve impulses. The white matter of the brain is composed of nerve fibers covered in myelin.

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Other Word Forms

• myelinic
  adjective

Etymology

Origin of myelin

First recorded in 1865–70; myel- + -in ²

Example Sentences

See Examples For:

myelin

These precursor cells can mature into oligodendrocytes, which produce the myelin sheath surrounding axons.

From Science Daily ● Aug. 14, 2026

They also have a major role in building myelin as the brain matures.

From Science Daily ● Aug. 14, 2026

Multiple sclerosis is caused by the immune system attacking the protective covering around nerve cells - known as myelin.

From BBC ● Jul. 22, 2026

In MS, researchers believe that these cells may take in so much damaged myelin that they eventually exceed their capacity to process it.

From Science Daily ● Jun. 29, 2026

Throughout adolescence, the brain is busily lining important neural pathways with a fatty sheath called myelin.

From "The 57 Bus" by Dashka Slater