Fig. (1).

Blood-brain barrier and the tight junction. (A) Schematic outline of a capillary of the blood-brain barrier in a transverse section showing the endothelium with a tight junction, basement membrane, a pericyte, and astrocytes. The localization of a gap junction between end-feet of the astrocytes is conceptually shown. (B) An electron micrograph showing a typical mammalian endothelial cell combined with a tight junction (arrows) and cationized ferritin (arrowheads) bound to the luminal endothelial surface representing the endothelial glycocalyx. There are scarce vesicular structures in the typical ECs of the brain.