Oligodendrocyte

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Oligodendrocyte

Oligodendrocytes (from Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
literally meaning cells with a few branches), or oligodendroglia (Greek, few tree glue), are a variety of neuroglia.

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style="font-size: larger;" | **Oligodendrocyte**
General Information

Tissue type	Nervous Nervous tissue Nervous tissue is one of four major classes of vertebrate Biological tissue. The function of the nervous tissue is in communication between parts of the body....
Cell type	Neuroglia
Location	Central nervous system Central nervous system The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
Role	Myelination Myelin Myelin is an electrically-insulating dielectric material that forms a layer, the myelin sheath. Usually, myelin surrounds only the axon of a neuron....
Identification	Robertson, 1899
Ultrastructure
Soma size	10–20µm Micrometre A micrometre or micron is one Micro- of a metre, or equivalently one thousandth of a millimetre. It is also commonly known as a micron....
Unique organelles	None
Unique feature	Myelinating processes

Oligodendrocytes (from Greek

Greek language

Axon

An axon or nerve fiber is a long, slender projectionof a nerve cell, or neuron, that conducts action potentialaway from the neuron's cell body or soma....
s exclusively in the central nervous system

Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
of the higher vertebrates, a function performed by Schwann cell

Schwann cell

Named after the Germany physiologist Theodor Schwann, Schwann cells are a variety of glial cell that keep peripheral nerve fibres alive. In myelinated axons, Schwann cells form the myelin sheath ....
s in the peripheral nervous system

Peripheral nervous system

The peripheral nervous system resides or extends outside the central nervous system , which consists of the brain and spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs....
. A single oligodendrocyte can extend to up to 50 axon

Axon

An axon or nerve fiber is a long, slender projectionof a nerve cell, or neuron, that conducts action potentialaway from the neuron's cell body or soma....
s, wrapping around approximately 1 mm of each and forming the myelin sheath; Schwann cells, on the other hand, can only wrap around 1 axon.

Origin

Oligodendroglia arise during development from an oligodendrocyte precursor cell

Oligodendrocyte precursor cell

Oligodendrocyte precursor cell in nervous tissue cells precede oligodendrocytes, and may also be able to generate neurons and astrocytes. The principle function of oligodendrocytes is to provide support to axons and to produce the Myelin sheath, which insulates and lowers the effective capacitance of axons....
, which can be identified by its expression of a number of antigens, including the ganglioside

Ganglioside

Ganglioside is a compound composed of a glycosphingolipid with one or more sialic acids linked on the sugar chain. The 60+ known gangliosides differ mainly in the position and number of NANA residue s....
GD3 , the NG2

NG2

NG2 is a Puerto Rico Salsa music duo formed by Norberto V?lez and Gerardo Rivas. Rivas is the son of Jerry Rivas, one of the singers of El Gran Combo....
chondroitin sulfate proteoglycan , and the platelet

Platelet

Platelets, or Thrombocyte, are small, irregularly shaped anuclear cells, 2-4?m in diameter, which are derived from fragmentation of precursor megakaryocytes....
-derived growth factor-alpha receptor subunit PDGF-alphaR . In the rat forebrain the majority of oligodendroglial progenitors arise during late embryogenesis and early postnatal development from cells of the subventricular zone

Subventricular zone

Subventricular zone is a paired brain structure situated throughout the lateral walls of the lateral ventricles. Along with the subgranular zone of dentate gyrus, the subventricular zone serves as a source of neural stem cells in the process of adult neurogenesis....
s (SVZ) of the lateral

Human anatomical terms

Human anatomical terms make up a distinct Scientific classification to describe areas of the body, to provide orientation when describing parts of human anatomy, and to distinguish different movements of the body....
ventricles. SVZ cells migrate away from these germinal

Germinal

Germinal is the thirteenth novel in ?mile Zola's twenty-volume series Les Rougon-Macquart. Widely considered Zola's undisputed masterpiece and one of the greatest novels ever written in the French language, the novel - an uncompromisingly harsh and realistic story of a coalminers' strike in northern France in the 1860s - has been pub...
zones to populate both developing white and gray matter, where they differentiate and mature into myelin

Myelin

Myelin is an electrically-insulating dielectric material that forms a layer, the myelin sheath. Usually, myelin surrounds only the axon of a neuron....
-forming oligodendroglia . However, it is not clear whether all oligodendroglial progenitors undergo this sequence of events. It has been suggested that some undergo apoptosis

Apoptosis

Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Programmed Cell death involves a series of biochemical events leading to a characteristic cell Morphology and death, in more specific terms, a series of biochemical events that lead to a variety of morphological changes, including Bleb , changes...
and that some fail to differentiate into oligodendroglia but persist into maturity as adult oligodendroglial progenitors .

Function

The nervous system

Nervous system

The nervous system is a Neural network of specialized cells that communicate information about an animal's surroundings and itself. It processes this information and causes reactions in other parts of the body....
of mammals depends crucially on the myelin sheath for insulation as it results in decreased ion leakage and lower capacitance of the cell membrane

Cell membrane

The cell membrane is the interface between the cellular machinery inside the cell and the fluid outside.It is a semipermeable lipid bilayer found in all cell ....
. There is also an overall increase in impulse speed as saltatory propagation

Saltatory conduction

Saltatory conduction is a means by which action potentials are transmitted along myelinated axons....
of action potential

Action potential

An action potential is a self-regenerating wave of electrochemical activity that allows nerve cells to carry a signal over a distance. It is the primary electrical signal generated by nerve cells, and arises from changes in the permeability of the nerve cell's axonal Cell membranes to specific ions....
s occurs at the nodes of Ranvier

Nodes of Ranvier

Nodes of Ranvier are the gaps formed between the myelin sheaths generated by different cells. A myelin sheath is a many-layered coating, largely composed of a fatty substance called myelin, that wraps around the axon of a neuron and very efficiently insulates it....
in between Schwann cells (of the PNS

Peripheral nervous system

Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
); 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.

Pathology

Diseases that result in injury to the oligodendroglial cells include demyelinating diseases such as multiple sclerosis

Multiple sclerosis

Multiple sclerosis is an autoimmune disease in which the immune system attacks the central nervous system, leading to demyelinating disease. Disease onset usually occurs in young adults, and it is more common in females....
and leukodystrophies

Leukodystrophy

Leukodystrophy refers to a group of disorders characterized by progressive degeneration of the white matter of the brain. The leukodystrophies are caused by imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fibers....
. 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 . Oligodendroglia are also susceptible to infection by the JC virus

JC virus

The JC virus or John Cunningham virus is a type of human polyomavirus and is genetically similar to BK virus and SV40. It was discovered in 1971 and named after the two initials of a patient with progressive multifocal leukoencephalopathy ....
, which causes progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy , also known as progressive multifocal leukoencephalitis, is a rare and usually fatal virus disease that is characterized by progressive damage or inflammation of the white matter of the brain at multiple locations ....
(PML), a condition which specifically affects white matter, typically in immunocompromised

Immunosuppression

Immunosuppression involves an act that reduces the activation or efficacy of the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other conditions....
patients. Tumor

Tumor

A tumor or tumour is the name for a swelling or lesion formed by an abnormal growth of cells . Tumor is not synonymous with cancer. A tumor can be Benign neoplasm, Carcinoma in situ or malignant, whereas cancer is by definition malignant....
s of oligodendroglia are called oligodendrogliomas

Oligodendroglioma

Oligodendrogliomas are a type of glioma that are believed to originate from the oligodendrocytes of the brain or from a glial precursor cell. They occur primarily in adults but are also found in children ....
.

External Links

The Department of Neuroscience at Wikiversity

Oligodendrocyte

Origin

Function

Pathology

See also

External Links