Glia | EPFL Graph Search

Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. The neuroglia make up more than one half the volume of neural tissue in our body. They maintain homeostasis, form myelin in the peripheral nervous system, and provide support and protection for neurons. In the central nervous system, glial cells include oligodendrocytes, astrocytes, ependymal cells and microglia, and in the peripheral nervous system they include Schwann cells and satellite cells. They have four main functions: to surround neurons and hold them in place to supply nutrients and oxygen to neurons to insulate one neuron from another to destroy pathogens and remove dead neurons. They also play a role in neurotransmission and synaptic connections, and in physiological processes such as breathing. While glia were thought to outnumber neurons by a ratio of 10:1, recent studies using newer methods and reappraisal of historical quantitative evidence suggests an overall ratio of less than 1:1, with substantial variation between different brain tissues. Glial cells have far more cellular diversity and functions than neurons, and glial cells can respond to and manipulate neurotransmission in many ways. Additionally, they can affect both the preservation and consolidation of memories. Glia were discovered in 1856, by the pathologist Rudolf Virchow in his search for a "connective tissue" in the brain. The term derives from Greek γλία and γλοία "glue" (ˈɡliːə or ˈɡlaɪə), and suggests the original impression that they were the glue of the nervous system. Derived from ectodermal tissue. Microglia Microglia are specialized macrophages capable of phagocytosis that protect neurons of the central nervous system. They are derived from the earliest wave of mononuclear cells that originate in yolk sac blood islands early in development, and colonize the brain shortly after the neural precursors begin to differentiate.