Astrocytes are a type of non-neuronal glial cell within the brain and spinal cord, believed to play roles in maintaining the blood-brain barrier, neurotransmitter uptake and release, and supporting neuronal cells. Astrocytes are morphologically diverse, with types such as fibrous (in white matter), protoplasmic (in grey matter), and radial. In identifying this cell type, some astrocyte markers that have been used include S100B, GFAP, glutamine synthetase, ALDH1L1, GLT1, and Glast. Antibodies against these markers may serve as useful tools in studying astrocytes.