Dictionary.net

a mechanism that creates a barrier between brain tissues and circulating blood; serves to protect the central nervous system; "the brain was protected from the large molecules of the virus by the blood-brain barrier"

a mechanism that creates a barrier between brain tissues and circulating blood; serves to protect the central nervous system; "the brain was protected from the large molecules of the virus by the blood-brain barrier"

Specialized non-fenestrated tightly-joined endothelial cells (tight junctions) that form a transport barrier for certain substances between the cerebral capillaries and the brain tissue.