Blood-brain barrier components

Thanks for the answer. I am CONCLUDING . The blood- brain barrier is not a single barrier,but a composite of many systems that act to control the entity of substance from the blood to brain. 1. Capillary endothelial cells linked by tight junctions and expressing specified uptake system for particular metabolic substrates ( eg glucose,aminoacids). 2.A permanent BASEMENT MEMBRANEbetween endothelia and adjacent cells. 3. Pericapillary astrocytes with end- feet adjacent to capillaries 4.Similar system exists for the choroidal epithelium( blood- cerebrospinal fluid( CSF ) barrier).
Various components make up the blood-brain barrier in addition to brain endothelial cells: pericytes; astrocyte end feet; microglia; and a basement membrane made from structural proteins such as the extracellular matrix proteins collagen and laminin.
Correctly I wrote the conclusion.kindly go through req to write the heading that came as duplicate. Very easy to understand.
Blood- brain barrier- components