MICROANATOMY

Detailed explanation-1: -Structure. The tunica externa is made from collagen and elastic fibers in a loose connective tissue.

Detailed explanation-2: -All vessels have an intima, which consists of a monolayer of endothelial cells and an underlying basal lamina composed of mesh-like type IV collagen and the adhesion molecules, fibronectin and laminin.

Detailed explanation-3: -Tunica adventitia or tunica externa is the outer layer of the blood vessel wall. It consists of connective tissue with vasa and nervi vasorum and plays a key role in vascular health.

Detailed explanation-4: -The outer tunic, the tunica externa (also called the tunica adventitia), is a substantial sheath of connective tissue composed primarily of collagenous fibers. Some bands of elastic fibers are found here as well. The tunica externa in veins also contains groups of smooth muscle fibers.