Internal elastic lamina
The internal elastic lamina or internal elastic lamella is a layer of elastic tissue that forms the outermost part of the tunica intima
Tunica intima
The tunica intima is the innermost layer of an artery or vein. It is made up of one layer of endothelial cells and is supported by an internal elastic lamina...

 of blood vessels. It readily visualized with light microscropy in sections of muscular arteries
Distributing artery
Distributing arteries are medium-sized arteries that draw blood from an elastic artery and branch into "resistance vessels" including small arteries and arterioles...

, where it is thick and prominent, and arterioles, where it is slightly less prominent and often incomplete. It is very thin in veins and venules. In elastic arteries such as the aorta, which have very regular elastic laminae between layers of smooth muscle
Smooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...

 cells in their tunica media
Tunica media
The tunica media is the middle layer of an artery or vein.-Artery:It is made up of smooth muscle cells and elastic tissue...

, the internal elastic lamina is approximately the same thickness as the other elastic laminae that are normally present.
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