The blood-brain barrier

The blood-brain barrier

Between the brain interstitium and plasma is located blood-brain barrier. Neighboring endothelial cells are connected by tight junctions that prevent the free diffusion of plasma constituents into the brain

A few small areas of the brain lack a blood-brain barrier (posterior pituitary, pineal gland). This arrangement allows certain neurons to be directly exposed to solutes in the blood, which facilitates some neuroendocrine control processes.