Fig. (1).

Components of blood brain barrier: Cerebral microvascular endothelial cells connected by tight junctions form the internal layer of the microvessel wall, which is embedded in the extracellular matrix, known as the basement membrane. Pericytes insert into the basement membrane and encircle the internal layer of microvessel wall and part of the basement membrane. The end-feet from different astrocytes cover the surface of pericytes, forming the outer layer of the microvessel wall. The functions of endothelial cells and astrocytes can be integrated by the pericyte though polarization of the astrocytic end-feet. (A higher resolution / colour version of this figure is available in the electronic copy of the article).