endothelium

noun

en·​do·​the·​li·​um ˌen-də-ˈthē-lē-əm How to pronounce endothelium (audio)
-dō-
plural endothelia ˌen-də-ˈthē-lē-ə How to pronounce endothelium (audio)
-dō-
1
: an epithelium of mesodermal origin composed of a single layer of thin flattened cells that lines internal body cavities and the lumens of vessels
2
: the inner layer of the seed coat of some plants
endothelial adjective

Examples of endothelium in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The virus that causes covid can affect the vascular endothelium — specialized cells that line blood vessels and help with blood flow, Rasmussen said. Kff Health News, Oc Register, 2 June 2025 Healthy endothelium cells also play a role in local cell growth and help prevent blood clotting. Sandee Lamotte, CNN Money, 28 May 2025 Aging and menopause contribute to the dysfunction of the endothelium (cells of blood vessels). Merve Ceylan, Health, 27 Dec. 2024 These complexes establish productive cellular infections in macrophages that result in the release of high concentrations of toxic NS1, a viral protein that damages cells' endothelium and produces dengue shock syndrome. Scientific American, 1 Jan. 2024 The corneal endothelium is a thin layer of cells that forms the inner lining of the cornea. William A. Haseltine, Forbes, 17 Feb. 2024 The innermost layer is known as the endothelial layer; exercise has been shown to influence the activity of the endothelium. Amber Sayer, Health, 25 Sep. 2023 Mamta Jain, $2.5 million for screening, treatment and prevention of Hepatocellular Cancer-Hepatitis C. Lance S. Terada, $1.05 million for autophagy and tumor endothelium. Dallas News, 16 Feb. 2023 The root of the problem is that even small amounts of the chemicals in cigarette smoke cause rapid inflammation in the endothelium, or lining, of blood vessels and in the lungs. Andrew Moseman, Discover Magazine, 10 Dec. 2010

Word History

Etymology

New Latin, from end- + -thelium (as in epithelium)

First Known Use

1872, in the meaning defined at sense 1

Time Traveler
The first known use of endothelium was in 1872

Browse Nearby Words

Cite this Entry

“Endothelium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/endothelium. Accessed 14 Jun. 2025.

Medical Definition

endothelium

noun
en·​do·​the·​li·​um ˌen-də-ˈthē-lē-əm How to pronounce endothelium (audio)
plural endothelia -lē-ə How to pronounce endothelium (audio)
: an epithelium of mesoblastic origin composed of a single layer of thin flattened cells that lines internal body cavities (as the serous cavities or the interior of the heart)

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