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Oligodendrocyte progenitor cells (OPCs), also known as oligodendrocyte precursor cells, NG2-glia or polydendrocytes, are a subtype of glial cells in the central nervous system. They are precursors to oligodendrocytes and may also be able to differentiate into neurons and astrocytes. Differentiated oligodendrocytes support axons and provide electrical insulation in the form of a myelin sheath, enabling faster action potential propagation and high fidelity transmission without a need for an increase in axonal diameter. The loss or lack of OPCs, and consequent lack of differentiated oligodendrocytes, is associated with a loss of myelination and subsequent impairment of neurological functions. == Description == Oligodendrocyte progenitor cells are a subtype of glial cells in the central nervous system, characterized by expression of the proteoglycans PDGFRA, and CSPG4.〔 OPCs are smaller than neurons, of comparable size to other glia, and can either have a bipolar or complex multipolar morphology with processes reaching up to ~50 um. OPCs encompass approximately 3-4% of cells in the grey matter and 7-8% in white matter, making them the fourth largest group of glia after astrocytes, microglia and oligodendrocytes. OPCs are particularly prevalent in the hippocampus and in all layers of the neocortex. In white matter, OPCs are found along unmyelinated axons as well as along myelinated axons, engulfing nodes of Ranvier. Recently, OPCs have been shown to reside in close contact with NG2-expressing pericytes in cerebral white matter, as well. OPCs have a remarkable homogenic distribution throughout the brain. This is achieved through active self-repulsion, causing the cells to be generally equally spaced from one another.〔 OPCs constantly survey their surroundings through actively extending and retracting growth cones. Death or differentiation of an OPC is rapidly followed by migration or local proliferation of a neighbouring cell. OPCs receive synaptic contacts onto their processes from both glutamatergic and GABAergic neurons.〔 Recently, it has been shown that OPCs receive preferred somatic contacts from fast-spiking GABAergic neurons, while non-fast spiking interneurons have a preference for contacting the processes. These inhibitory connections have been shown in mice to occur mainly during a very specific period in development, from postnatal day 8 till postnatal day 13. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Oligodendrocyte progenitor cell」の詳細全文を読む スポンサード リンク
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