The endothelium is a continuous monolayer formed by cells linked to each other by different types of adhesive structures. These are involved in the control of vascular permeability to plasma proteins and circulating cells, and contribute to the establishment of cell polarity by limiting the diffusion of lipid and transmembrane proteins in the outer leaflet of the plasma membrane bilayer (1).

A major ubiquitous type of endothelial cell–cell junctions are adherens junctions. The general organization of adherens junctions presents many structural and functional similarities in different cell types but its molecular components and biological meaning may vary in the different tissues. In recent years excellent reviews (3–9) have extensively considered the molecular organization and signaling properties of adherens junctions. The present review is devoted to the special properties of these structures in the endothelium and offers some insights on their role in the control of endothelial cell permeability and vascular morphogenesis. Adherens junctions are formed by transmembrane adhesive proteins, belonging to the cadherin family, that are organized in clusters at cell–cell contacts and connect through their cytoplasmic domain with a complex network of cytoskeletal proteins (3–9).