The microvasculature of the brain is important in the normal development and maintenance of the blood-brain barrier. Since glial cells are in close contact with brain capillaries in situ , communication between glial cells and capillary endothelial cells is thought to be important in maintaining homeostasis within the central nervous system. The selective permeability barrier, termed the blood-brain barrier, is maintained by specific membrane transport systems and tight junctions between adjacent endothelial cells. (Patho)physiological stresses such as anoxia, ischemia, metabolic, and/or degenerative disturbances, affect the endothelium, and in turn, affect the selective permeability barrier. Brain capillary endothelial cells in culture would facilitate the study of the mechanisms involved in cerebral vascular injury.