The BBB is composed of several cellular and acellular components. The primary cellular components are the endothelial cells of the brain capillaries, which are interconnected by tight junctions. These endothelial cells differ from those in other parts of the body by having fewer pinocytotic vesicles and a higher density of mitochondria. The acellular components include the basement membrane and the extracellular matrix. Additionally, astrocytes and pericytes play supportive roles in BBB function.
