Vessels With Cingulin Are Leakproof.

The endothelium, once thought of as a cellophane-like inner lining for blood vessels, is now known as a selective barrier between blood and the surrounding tissue. Endothelial cells (ECs) specialize their barrier function, as in brain ECs, where the blood–brain barrier protects neurons against toxins, or in liver ECs, where they are highly fenestrated for efficient filtering of the blood. Angiogenesis also relies on regulation of EC junctions. Finally, barrier function plays a role in diseases such as atherosclerosis, where poor barrier maintenance allows increased monocyte extravasation. The increase in monocyte extravasation leads to macrophage colonization and the eventual buildup of plaques.