ABSTRACT
Endothelial cells and its layered form endothelium are indispensible structures in the body and are not a simple barrier or a layer separating the vascular smooth muscle from circulating blood. Its functional properties are more important than being a simple layer (Whyte and Laughlin 2010). It has very complex functions both on health and dysfunctional conditions. William Harvey was the fi rst to state that blood was circulating in a closed system and the word “endothelium” was fi rst articulated by Wilhelm His in 1865 (Aird 2007).
