In addition to protoplasmic and fibrous forms, regional specialization occurs among astrocytes. The outer membranes of astrocytes located in subpial zones and adjacent to blood vessels possess a specialized thickening. Desmosomes and gap junctions are very common in these regions between astrocytic processes. In the cerebellar cortex, protoplasmic astrocytes can be segregated into three classes, each ultrastructurally distinct: the Golgi epithelial cell, the lamellar or velate astrocyte and the smooth astrocyte [1].