myelin

noun

my·​e·​lin ˈmī-ə-lən 

: 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

myelinic

ˌmī-ə-ˈli-nik 

adjective

Examples of myelin in a Sentence

Recent Examples on the Web

Your body also needs the mineral to help make myelin, a protein that wraps protectively around nerve cells to help amplify all those signals. —Lizzy Briskin, SELF, 26 Mar. 2024

While the cause is unknown, MS attacks the central nervous system, creating lesions on the brain and spinal cord, and damaging the protective layer surrounding the nerve fibers, called myelin. —Andrew Abrahams, Peoplemag, 1 Mar. 2024

Though the exact cause of multiple sclerosis is unknown, the disease triggers the immune system to attack the central nervous system — resulting in damage to the protective layer surrounding the nerve fibers, called myelin, and disrupting signals to and from the brain. —Julie Jordan, Peoplemag, 15 Nov. 2023

The disease causes the immune system to attack myelin, the insulation around nerve fibers, prompting symptoms that can include muscle weakness, pain, and vision loss. —Kenneth Miller, Discover Magazine, 11 Dec. 2023

In Emma’s case, the combination of mutations appears to affect her brain’s myelin, the protective sheathing that covers our nerves and brain cells, says Carlos Bacino, a clinical geneticist at the Baylor College of Medicine, a UDN site, and Emma’s physician at Texas Children’s Hospital. —Nathaniel Scharping, Discover Magazine, 18 June 2021

An analogy sometimes given is that the nervous system is like the wiring of a lamp, and the myelin like the wiring’s protective sheath; when that sheath wears away, so much can go wrong. —Rivka Galchen, The New Yorker, 17 July 2023

To pull that off, axons are insulated with myelin, a fatty substance that speeds transmission. —Lydia Denworth, Scientific American, 1 Aug. 2021

Degrading myelin leads to communication difficulties between neurons and their connections with the rest of the body. —Kristine Zengeler, Discover Magazine, 10 Dec. 2022

Word History

Etymology

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 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

First Known Use

1866, in the meaning defined above

Phrases Containing myelin

• myelin sheath

Kids Definition

myelin

noun

my·​elin

ˈmī-ə-lən

: a soft white somewhat fatty material that forms a thick layer around the axons of some neurons

Medical Definition

myelin

noun

my·​e·​lin ˈmī-ə-lən 

: 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

myelinic

ˌmī-ə-ˈlin-ik 

adjective