: 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
Examples of myelin in a Sentence
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However, myelin can also be a source of energy during extreme metabolic conditions, such as running a marathon.
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Monica Cull, Discover Magazine, 3 July 2025
The body uses vitamin B12 to synthesize myelin, a substance made from fats and proteins that surrounds and insulates nerves.
—Kaitlin Sullivan, NBC news, 2 July 2025
However, their myelin levels returned to normal within two months of the race.
—Monica Cull, Discover Magazine, 3 July 2025
When depleted of other energy sources, the brains of marathon runners consume their own myelin.
—Rafil Kroll-Zaidi, Harpers Magazine, 18 June 2025
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Monica Cull, Discover Magazine, 3 July 2025
The body uses vitamin B12 to synthesize myelin, a substance made from fats and proteins that surrounds and insulates nerves.
—Kaitlin Sullivan, NBC news, 2 July 2025
However, their myelin levels returned to normal within two months of the race.
—Monica Cull, Discover Magazine, 3 July 2025
When depleted of other energy sources, the brains of marathon runners consume their own myelin.
—Rafil Kroll-Zaidi, Harpers Magazine, 18 June 2025
See All Example Sentences for myelin
Cite this Entry
“Myelin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/myelin. Accessed 31 Jul. 2025.
Copy CitationMedical 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
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