Structure of intercellular junctions in the endothelium.

Endothelial cell junctions are complex structures formed by transmembrane adhesive molecules linked to a network of cytoplasmic/cytoskeletal proteins. At least three different types of endothelial junctions have been described: tight junctions, gap junctions and adherens junctions. These structures have some features and components in common with epithelium but also some which are specific for endothelium. We still know very little about the pathologic consequences of alterations in the functional behaviour or synthesis of endothelial cell junction proteins. It is possible that pathologies linked to altered endothelial permeability and vascular organization (e.g. hemangiomas, scleroderma, and other types of vasculitis) are associated with structural alterations in endothelial junction organization. In addition, changes in endothelial permeability properties are associated with the early stages of atherosclerosis and many inflammatory diseases.