Diagnosis: Blood-brain barrier
• The blood-brain barrier (BBB) is formed by intercellular tight junctions between brain microvascular endothelial cells. The supporting layer is composed of a basal lamina, pericytes, and the ends of astrocytic processes. These cellular interactions promote and stabilize the tight junctions.
• Disruption of the BBB is common in a great many neuropathologies, including metastases, high grade gliomas, infections, demyelinating diseases, infarctions, hemorrhages, and trauma.
• Neither metastatic neoplasms to the central nervous system (CNS) nor high grade gliomas maintain a full, functional BBB in part because of the disruption of the normal astrocyte-blood vessel interactions and a consequent loss of tight junctions between endothelial cells.
• In the choroid plexus, the endothelial cells of the vessels are not linked by tight junctions but rather are fenestrated;however, tight junctions between epithelial cells of the choroid plexus restrict passage of some blood components into the CSF. Many CSF proteins are transported across choroid plexus epithelial cells or synthesized and secreted by the epithelial cells.
