Gap cell junction created between two neighboring cells by connexin.
In the central nervous system, pericytes wrap around the endothelial cells that line the inside of the capillary. These two types of cells can be easily distinguished from one another based on the presence of the prominent round nucleus of the pericyte compared to the flat elongated nucleus of the endothelial cells. Pericytes also project finger-like extensions that wrap around the capillary wall, allowing the cells to regulate capillary blood flow.
Both pericytes and endothelial cells share a basement membrane where a variety of intercellular connections are made. Many types of integrin molecules facilitate communication between pericytes and endothelial cells separated by the basement membrane. Pericytes can also form direct connections with neighboring cells by forming peg and socket arrangements in which parts of the cells interlock, similar to the gears of a clock. At these interlocking sites, gap junctions can be formed which allow the pericytes and neighboring cells to exchange ions and other small molecules. Important molecules in these intercellular connections include N-cadherin, fibronectin, connexin and various integrins.
In some regions of the basement membrane, adhesion plaques composed of fibronectin can be found. These plaques facilitate the connection of the basement membrane to the cytoskeletal structure composed of actin, and the plasma membrane of the pericytes and endothelial cells.