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Oligodendrocytes are a type of glial cell, non-neuronal cells in the central nervous system.They arise during development from oligodendrocyte precursor cells (OPCs), [8] which can be identified by their expression of a number of antigens, including the ganglioside GD3, [9] [10] [11] the NG2 chondroitin sulfate proteoglycan, and the platelet-derived growth factor-alpha receptor subunit (PDGF ...
Myelin is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.Therefore, the first stage of myelinogenesis is often defined as the differentiation of oligodendrocyte progenitor cells (OPCs) or Schwann cell progenitors into their mature counterparts, [4] followed by myelin formation around axons.
This schematic illustrates the four different types of glial cells, all of which possess cytoplasmic processes: ependymal cells (light pink), astrocytes (green), microglia (red), and oligodendrocytes (light blue). Cell bodies of neurons are in yellow (Their axons are surrounded by myelin, produced by oligodendrocytes).
Oligodendrocyte progenitor cells (OPCs), also known as oligodendrocyte precursor cells, NG2-glia, O2A cells, or polydendrocytes, are a subtype of glia in the central nervous system named for their essential role as precursors to oligodendrocytes and myelin. [1]
Oligodendrocytes are found in the CNS and resemble an octopus: they have bulbous cell bodies with up to fifteen arm-like processes. Each process reaches out to an axon and spirals around it, creating a myelin sheath. The myelin sheath insulates the nerve fiber from the extracellular fluid and speeds up signal conduction along the nerve fiber. [34]
Myelin's best known function is to increase the rate at which information, encoded as electrical charges, passes along the axon's length. Myelin achieves this by eliciting saltatory conduction. [1] Saltatory conduction refers to the fact that electrical impulses 'jump' along the axon, over long myelin sheaths, from one node of Ranvier to the next.
The neurilemma is underlain by the myelin sheath (also known as the medullary sheath). In the central nervous system , axons are myelinated by oligodendrocytes , thus lack neurilemma. The myelin sheaths of oligodendrocytes do not have neurilemma because excess cytoplasm is directed centrally toward the oligodendrocyte cell body.
Glia are the supporting cells of the neurons and have many functions not all of which are clearly understood, but include providing support and nutrients to the neurons. Glia are grouped into macroglia – astrocytes, ependymal cells, and oligodendrocytes, and much smaller microglia which are the macrophages of the central nervous system.