External elastic lamina

The adventitia is separated from the media by a discontinuous sheet of elastic tissue (the external elastic lamina) and consists of smooth muscle cells, fibroblasts, collagen fibers, and glycosaminoglycans. This layer is supplied with blood vessels to provide nutrients. 

The normal artery is composed of three distinct layers (Fig. 34.21). That which is closest to the lumen of the vessel, the intima, is lined by a monolayer of endothelial cells that are bathed by the circulating blood. Just beneath these specialized cells lies the subintimal extracellular matrix, in which some vascular smooth muscle cells are embedded (the subintimal space). The middle layer, known as the tunica media, is separated from the intima by the internal elastic lamina. The tunica media contains lamellae of smooth muscle cells surrounded by an elastin- and collagen-rich matrix. The external elastic lamina forms the border between the tunica media and the outermost layer, the adventitia. This layer contains nerve fibers and mast cells. It is the origin of the vasa vasorum, which supply blood to the outer two thirds of the tunica media. 

Wall morphology Complete tunica adventitia, external elastic lamina, tunica media, internal elastic lamina, tunica intima. ... 

Well-developed tunica media and external elastic lamina, but tunica adventitia virtually nonexistent) ... 

A well-developed endothelium, subendothelium, and internal elastic lamina, plus about two to three 15 /rm thick concentric layers forming just a very thin tunica media no external elastic lamina)... 

The tunica media contains predominantly smooth muscle cells and elastin fibres that are much more highly organized in larger arteries due to the role required in the movement of large volumes of blood. Additional structural support is provided by an external elastic lamina. The remaining and outermost layer of the blood vessel is the tunic adventitia that is composed almost entirely of fibro-elastic connective tissue. Lymphatic and nerve plexi are found in the adventitia along with the vasa... 

Complete tunica adventitia, external elastic lamina, tunica media, internal elastic lamina, tunica intima, subendothelium, endothelium, and vasa vasorum vascular supply Main branches 32 5 mm-2.25 cm 3.3-6 cm —2 mm 83.2 ml... 

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