Which glial cell forms the blood-brain barrier?

Which glial cell forms the blood-brain barrier?

• A. Microglia
• B. Astrocytes
• C. Oligodendrocytes
• D. Ependymal cells

Answer: (B)

Astrocytes are the glial cells that form the blood-brain barrier. Their endfeet wrap around brain capillaries and release signals that promote and maintain the tight junctions between endothelial cells, creating the highly selective barrier that protects the brain. This neurovascular unit—the endothelial cells with astrocyte endfeet—controls what can pass from blood into neural tissue and helps regulate the brain’s ionic environment and nutrient supply. Other glial cells have different roles: microglia act as immune cells, oligodendrocytes insulate axons with myelin, and ependymal cells line the ventricles and help produce cerebrospinal fluid.

Astrocytes are the glial cells that form the blood-brain barrier. Their endfeet wrap around brain capillaries and release signals that promote and maintain the tight junctions between endothelial cells, creating the highly selective barrier that protects the brain. This neurovascular unit—the endothelial cells with astrocyte endfeet—controls what can pass from blood into neural tissue and helps regulate the brain’s ionic environment and nutrient supply. Other glial cells have different roles: microglia act as immune cells, oligodendrocytes insulate axons with myelin, and ependymal cells line the ventricles and help produce cerebrospinal fluid.