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07-SEPTEMBER-2008 03:17:44 - Oligodendrocyte Redirected from Oligodendrocytes Oligodendrocyte Oligodendrocyte General Information Tissue type Nervous Cell type Neuroglia Location Central nervous system Role Myelination Identification Robertson, 1899 Ultrastructure Soma size 10-20μm Unique organelles None Unique feature Myelinating processes Oligodendrocytes from Greek literally meaning cells with a few branches, or oligodendroglia Greek, few tree glue,1 are a variety of neuroglia. Their main function is the insulation of the axons exclusively in the central nervous system of the higher vertebrates, a function performed by Schwann cells in the peripheral nervous system. A single oligodendrocyte can extend to up to 50 axons, wrapping around approximately 1 mm of each and forming the myelin sheath; Schwann cells, on the other hand, can only wrap around 1 axon. Contents 1 Origin 2 Function 3 Pathology 4 See also 5 Notes 6 References Origin Oligodendroglia arise during development from an oligodendrocyte precursor cell, which can be identified by its expression of a number of antigens, including the ganglioside GD3 2, the NG2 chondroitin sulfate proteoglycan 3, and the platelet-derived growth factor-alpha receptor subunit PDGF-alphaR 4. In the rat forebrain the majority of oligodendroglial progenitors arise during late embryogenesis and early postnatal development from cells of the subventricular zones SVZ of the lateral ventricles. SVZ cells migrate away from these germinal zones to populate both developing white and gray matter, where they differentiate and mature into myelin-forming oligodendroglia 5. However, it is not clear whether all oligodendroglial progenitors undergo this sequence of events. It has been suggested that some undergo apoptosis 6 and that some fail to differentiate into oligodendroglia but persist into maturity as adult oligodendroglial progenitors 7. Function The nervous system of mammals depends crucially on the myelin sheath for insulation as it results in decreased ion leakage and lower capacitance of the cell membrane. There is also an overall increase in impulse speed as saltatory propagation of action potentials occurs at the nodes of Ranvier in between Schwann cells of the PNS and oligodendrocytes of the CNS; furthermore miniaturization occurs, whereby impulse speed of myelinated axons increases linearly with the axon diameter, whereas the impulse speed of unmyelinated cells increases only with the square root of the diameter. As part of the nervous system they are closely related to nerve cells and like all other glial cells the oligodendrocytes have a supporting role towards neurons. They are intimately involved in signal propagation, providing the same functionality as the insulation on a household electrical wire with the rather large difference that while household electrical wires are in a non-conducting medium - air - the axons run in a solution of water and ions that conduct electrical current well. Satellite oligodendrocytes are functionally distinct from most oligodendrocytes. They are not attached to neurons and therefore do not serve an insulating role. They remain close to neurons and regulate the extracellular fluid.8 Pathology Diseases that result in injury to the oligodendroglial cells include demyelinating diseases such as multiple sclerosis and leukodystrophies. Cerebral palsy periventricular leukomalacia is caused by damage to developing oligodendrocytes in the brain areas around the cerebral ventricles. Spinal cord injury also causes damage to oligodendrocytes. In cerebral palsy, spinal cord injury, stroke and possibly multiple sclerosis, oligodendrocytes are thought to be damaged by excessive release of the neurotransmitter glutamate. Oligodendrocyte dysfunction may also be implicated in the pathophysiology of schizophrenia and bipolar disorder 9. Oligodendroglia are also susceptible to infection by the JC virus, which causes progressive multifocal leukoencephalopathy PML, a condition which specifically affects white matter, typically in immunocompromised patients. Tumors of oligodendroglia are called oligodendrogliomas. See also 2',3'-Cyclic Nucleotide 3'-Phosphodiesterase Notes ^ Ragheb 1999, p. 14. ^ Curtis et al., 1988; LeVine and Goldman, 1988; Hardy and Reynolds, 1991; Levine et al., 1993 ^ Levine et al., 1993 ^ Pringle et al., 1992 ^ Hardy and Reynolds, 1991; Levison and Goldman, 1993 ^ Barres et al., 1992 ^ Wren et al., 1992 ^ Baumann and Pham-Dinh, 2001 ^ Tkachev et al., 2003 References Baumann, Nicole Danielle Pham-Dinh 2001, Biology of Oligodendrocyte and Myelin in the Mammalian Central Nervous System, Physiological Reviews 18 2: 871-927, http://physrev.physiology.org/cgi/content/full/81/2/871. Retrieved on 2007-07-13 Ragheb, Fadi 1999, written at Ottawa, The M3 Muscarinic Acetylcholine Receptor Mediates p42mapk Activation and c-fos mRNA Expression in Oligodendrocyte Progenitors, National Library of Canada, http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0025/MQ50862.pdf. Retrieved on 2006-03-07 Raine, C.S. 1991. Oligodendrocytes and central nervous system myelin. In Textbook of Neuropathology, second ion, R.L. Davis and D.M. Robertson, eds. Baltimore, Maryland: Williams and Wilkins, pp. 115-141. Tkachev D, Mimmack ML, Ryan MM, Wayland M, Freeman T, Jones PB, Starkey M, Webster MJ, Yolken RH, Bahn S. 2003. Oligodendrocyte dysfunction in schizophrenia and bipolar disorder. Lancet. 2003 Sep 6;3629386:798-805.PMID: 13678875 v d e Histology: nervous tissue Neurons gray matter soma - axon axon hillock, axoplasm, axolemma, neurofibril/neurofilament dendrite Nissl body, dendritic spine, apical dendrite, basal dendrite types: bipolar - pseudounipolar - multipolar - pyramidal - Purkinje - granule Afferent nerve/Sensory nerve/Sensory neuron GSA - GVA - SSA - SVA - fibers Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain Efferent nerve/Motor nerve/Motor neuron GSE - GVE - SVE - Upper motor neuron - Lower motor neuron α motorneuron, γ motorneuron Synapses neuropil - synaptic vesicle - neuromuscular junction - electrical synapse - Interneuron Renshaw Sensory receptors Meissner's corpuscle - Merkel nerve ending - Pacinian corpuscle - Ruffini ending - Muscle spindle - Free nerve ending - Olfactory receptor neuron - Photoreceptor cell - Hair cell - Taste bud Glial cells Astrocyte Radial glia - Oligodendrocyte - Ependymal cells Tanycytes - Microglia Myelination white matter CNS: Oligodendrocyte PNS: Schwann cell - Neurolemma - Nodes of Ranvier/Internode - Schmidt-Lanterman incisures Related connective tissues epineurium - perineurium - endoneurium - nerve fascicle - meninges Retrieved from http://en..org/wiki/Oligodendrocyte Categories: Neurology | Nervous system | Neurophysiology | Glial cells Views Article Discussion this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Go Search Interaction Community portal Recent changes Contact Donate to Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages Deutsch Español Ù?ارسی Français עברית Nederlands 日本語 Polski Português РуÑ?Ñ?кий This page was last modified on 5 June 2008, at 15:09
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