What is the epithelial lining of blood vessels called?

The epithelial lining of blood vessels is called endothelium. It is a specialized type of simple squamous epithelium that forms a smooth, protective layer lining the interior surface of blood vessels, including arteries, veins, and capillaries. The endothelium plays a crucial role in regulating vascular functions, including blood flow, inflammation, and the exchange of substances between the bloodstream and surrounding tissues.