A class of large neuroglial (macroglial) cells in the central nervous system - the largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from "star" cells) are irregularly shaped with many long processes, including those with "end feet" which form the glial (limiting) membrane. The cell body of an astrocyte spans 10-20 microns and its processes radiate out for another 20-30 microns. Astrocytes stain for the intermediate filament GFAP. Astrocytes are recognized in the transmission electron microscope by their irregular shape, numerous glycogen granules, a relatively clear cytoplasm and bundles of intermediate filaments (adapted from MSH and Synapse Web)., A class of large neuroglial (macroglial) cells in the central nervous system - the largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from "star" cells) are irregularly shaped with many long processes, including those with "end feet" which form the glial (limiting) membrane and directly and indirectly contribute to the blood-brain barrier. They regulate the extracellular ionic and chemical environment, and "reactive astrocytes" (along with microglia) respond to injury (MSH).

http://neurolex.org/wiki/Category:Astrocyte