The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall.[AAO]

uberon

Vertebrates and a very few invertebrates such as squids have evolved a secondary epithelium, the endothelium, that lines their blood vessels.[well established][VHOG]

UBERON:0001917

• dorsal aorta

• endothelial cell of artery