(from the ancient Greek ἄστρον, ástron, “star” and κύτος, kútos, “cavity”, “cell”), known collectively as astroglia, are characteristic stellate glial cells in the brain and spinal cord. They perform a variety of functions, including biochemical control of the endothelial cells that form the blood-brain barrier, the supply of nutrients to nervous tissue, the maintenance of extracellular ion balance, the regulation of cerebral blood flow, and a role in the process of brain and spinal cord repair and scarring after infection and traumatic injuries.