Structural and functional aspects of the blood-brain barrier

All organisms with a complex nervous system have a well-developed blood-central nervous system barrier. In the vertebrates the central nervous system (CNS) lies behind the protective blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB). In all mammals the BBB is formed at the level of the cerebral capillary endothelial cells and the BCSFB by the choroid plexus epithelium.