Terminology
The foundational model of anatomy makes a distinction between endothelial cells and epithelial cells on the basis of which tissues they develop from, and states that the presence of vimentin rather than keratin filaments separate these from epithelial cells. Many considered the endothelium a specialized epithelial tissue.
Both blood and lymphatic capillaries are composed of a single layer of endothelial cells called a monolayer.
Read more about this topic: Endothelium