Endothelium
/ˌɛn.doʊˈθiː.li.əm/noun
A thin layer of cells lining blood vessels, lymphatic vessels, and certain internal cavities.
Did you know?German anatomist Wilhelm His introduced the term Endothel in 1865, contrasting it with epithelium, because he viewed the tissue as an internal cellular lining.
Etymological Timeline
Proto-Indo-European
PIE
*en
“In, inside, or within”
Ancient Greek
Greek
endon
“Within or inside”
Ancient Greek
Greek
thēlē
“Nipple or teat”
1865
German
Endothel
“An internal cellular lining; the term was introduced by Wilhelm His”
Late 19th Century
New Latin
endothelium
“The specialized inner lining of vessels and cavities”
Modern English
English
endothelium
“The cellular lining of blood vessels, lymphatic vessels, and related internal surfaces”