myelin

noun my·e·lin \ ˈmī-ə-lən \

|Updated on: 13 Jun 2018

Definition of myelin

: a soft white material that forms a thick layer around the axons of some neurons and is composed chiefly of lipids (such as cerebroside and cholesterol), water, and smaller amounts of protein

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myelinic

play \ˌmī-ə-ˈli-nik\ adjective

See myelin defined for kids

Recent Examples of myelin from the Web

In cells that make myelin, the substance that insulates and protects nerves, an abundance of sulfatides destroys tissue throughout the brain, spinal cord, and other parts of the nervous system.

— vibhav rangarajan, STAT, "The ‘cruel joke’ of compassionate use and right to try: Pharma companies don’t have to comply," 5 June 2018
The ragged extensions of an oligodendrocyte can supply many neurons (nerve cells) with myelin, an insulating material which allows each neuron's communicating axon to transmit electrical impulses efficiently.

— doug criss, CNN, "5 things for March 28: North Korea & China, Sacramento, water park death, new organ," 28 Mar. 2018
Drugs like inhalants can change the structure of the nervous system by destroying myelin: the fatty substance that coats the nerves like insulation.

— stmichaelschool, cleveland.com, "St. Michael School Hosts Info Night and Open House: Community Voices," 13 Jan. 2018
In both types of MS, immune system cells attack and strip away myelin, the fatty protective sheathing that insulates nerve cells.

— linda marsa, Discover Magazine, "Beating B-Cells for MS," 1 Feb. 2018
Symptoms like foggy thinking and trouble walking, which Davis experienced, happen because multiple sclerosis attacks the protective sheath (myelin) that covers nerve fibers.

— mary lou brink, cleveland.com, "Top Workplaces 2018 nomination deadline extended," 21 Jan. 2018
The destruction of the myelin reduces the nerve's ability to function.

— stmichaelschool, cleveland.com, "St. Michael School Hosts Info Night and Open House: Community Voices," 13 Jan. 2018
This growth in connectivity presents itself as white matter in the brain, which comes from a fatty substance called myelin.

— alexandra sifferlin, Time, "Why Teenage Brains Are So Hard to Understand," 8 Sep. 2017
The ailment destroys the protective sheath surrounding the brain’s neurons—known as myelin—and if left untreated can lead to blindness, seizures, loss of muscle control and dementia.

— brian t. dessart, SI.com, "Patrick Lange, Daniela Ryf Set Records in Ironman World Championship Victories," 16 Oct. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'myelin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of myelin

International Scientific Vocabulary

NEW! Time Traveler

First Known Use: 1866

in the meaning defined above

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Medical Dictionary

myelin

noun my·e·lin \ ˈmī-ə-lən \

medical Definition of myelin

: a soft white material of lipid and protein that is secreted by oligodendrocytes and Schwann cells and forms a thick sheath about axons — see myelin sheath

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