my·​e·​lin | \ ˈmī-ə-lən How to pronounce myelin (audio) \

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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Other Words from myelin

myelinic \ ˌmī-​ə-​ˈli-​nik How to pronounce myelin (audio) \ adjective

Examples of myelin in a Sentence

Recent Examples on the Web The inflammation then damages the myelin that covers and protects the nerve fibers, the Mayo Clinic explains, which can cause sharp pain in the lower back, weakness in the limbs, odd sensations of numbness or tingling, and bowel or bladder issues. Sarah Jacoby, SELF, "AstraZeneca Halted Its COVID-19 Vaccine Trials After a Possible Serious Adverse Reaction," 10 Sep. 2020 One of the most surprising of these new findings involves myelin. R. Douglas Fields, Scientific American, "The Brain Learns in Unexpected Ways," 12 Mar. 2020 Drugs that control myelin production could provide new approaches to treating these problems. R. Douglas Fields, Scientific American, "The Brain Learns in Unexpected Ways," 12 Mar. 2020 The outer layer of myelin is attached to the axon adjacent to the perinodal astrocytes. R. Douglas Fields, Scientific American, "The Brain Learns in Unexpected Ways," 12 Mar. 2020 His research shows that when a mouse’s ears lose the myelin that insulates the neurons, the critter experiences the symptoms of hidden hearing loss, even though its synapses are fine. Popular Science, "Hidden hearing loss is hitting people of all ages. Neuroscientists are still debating why.," 21 Jan. 2020 Many misophonics have more myelin (which insulates neurons and speeds the spread of information) than average in the ventromedial prefrontal cortex, an area associated with quick decision-making. Popular Science, "Unlocking the mysterious ecstasy of ASMR—and its agonizing cousin," 18 Dec. 2019 Metachromatic leukodystrophy is the result of a genetic mutation, and leads to a breakdown of the protective covering around nerve cells and nerve fibers, known as myelin. Lisa Schencker,, "No. No. No. No. No. An insurer rejected out-of-state treatment for a 4-year-old’s rare disease five times. It relented, but why is getting an OK so hard?," 15 Nov. 2019 Without myelin, crucial signals between the brain and the body become garbled or simply go missing entirely. Aaron Gilbreath, Longreads, "The Inward Empire," 27 June 2018

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.

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First Known Use of myelin

1866, in the meaning defined above

History and Etymology for myelin

borrowed from German Myelin, from Greek myelós "bone marrow" + German -in -in entry 1 — more at myelo-

Note: The term was introduced by Rudolf virchow entry b in "Ueber das ausgebreitete Vorkommen einer dem Nervenmark analogen Substanz in den thierischen Geweben," Archiv für pathologische Anatomie und Physiologie und für klinische Medicin, 6. Band (1854), p. 571

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Cite this Entry

“Myelin.” Dictionary, Merriam-Webster, Accessed 7 May. 2021.

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More Definitions for myelin


my·​e·​lin | \ ˈmī-ə-lən How to pronounce myelin (audio) \

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

Other Words from myelin

myelinic \ ˌmī-​ə-​ˈlin-​ik How to pronounce myelin (audio) \ adjective

More from Merriam-Webster on myelin Encyclopedia article about myelin

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