cultures that are generated by O2A cells grown in the presence of fetal calf serum but are not thought to exist in vivo. Anatomical classification Protoplasmic: found in grey matter and have many branching processes whose end-feet envelop synapses. Some protoplasmic astrocytes are generated by multipotent subventricular zone progenitor cells. Gömöri-positive astrocytes. These are a subset of protoplasmic astrocytes that contain numerous cytoplasmic inclusions, or granules, that stain positively with Gömöri's chrome-alum hematoxylin stain. It is now known that these granules are formed from the remnants of degenerating mitochondria engulfed within lysosomes, Some type of oxidative stress appears to be responsible for the mitochondrial damage within these specialized astrocytes. Gömöri-positive astrocytes are much more abundant within the arcuate nucleus of the hypothalamus and in the hippocampus than in other brain regions. They may have a role in regulating the response of the hypothalamus to glucose. Fibrous: found in white matter and have long thin unbranched processes whose end-feet envelop nodes of Ranvier. Some fibrous astrocytes are generated by radial glia. Transporter/receptor classification GluT type: these express glutamate transporters (EAAT1/ and EAAT2/) and respond to synaptic release of glutamate by transporter currents. The function and availability of EAAT2 is modulated by TAAR1, an intracellular receptor in human astrocytes. GluR type: these express glutamate receptors (mostly mGluR and AMPA type) and respond to synaptic release of glutamate by channel-mediated currents and IP3-dependent Ca2+ transients. See also Bergmann gliosis Gemistocyte Pituicyte List of human cell types derived from the germ layers References Further reading External links Cell Centered Database – Astrocyte "Astrocytes" at Society for Neuroscience The Department of Neuroscience at Wikiversity NIF Search – Astrocyte via the Neuroscience Information Framework Central nervous system Glial cells Human cells