endothelium

Term: endothelium

Literally meaning: " internal epithelium”

Origin: Anc Greek

ενδο-/endo-(= compining form for “inside”, “internal”, “within”)

+επιθήλιο/epithelio(=epithelium)

>επί/epi(=on, upon)

θηλή/theli(=nipple) literally meaning “on nipple” because originally this word meant only the skin on the breast which is not identical to the epidermis and in literal translation it is a misnomer.

Coined/History

 The term was coined in 1865 by the Swiss embryologist and anatomist Wilhelm Hirsch for cell layer lining the lumen of the vscular system and inner cavities of the body . Some years later the term was restricted to its modern usage.  

Definition

The endothelium is the thin layer of cells that lines the interior surface of blood and lymph vessels.