Everything about Oligodendrocyte totally explained
Oligodendrocyte>
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|
| General Information |
Nervous
| Cell type |
Neuroglia |
| Location |
Central nervous system |
| Role |
Myelination |
| Identification |
Robertson, 1899 |
| Ultrastructure |
μm
| Unique organelles |
None |
| Unique feature |
Myelinating processes |
Oligodendrocytes (from
Greek literally meaning
cells with a few branches), or
oligodendroglia (Greek,
few tree glue), 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.
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, the
NG2 chondroitin sulfate proteoglycan, and the
platelet-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 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 . However, it isn't clear whether all oligodendroglial progenitors undergo this sequence of events. It has been suggested that some undergo
apoptosis and that some fail to differentiate into oligodendroglia but persist into maturity as adult oligodendroglial progenitors .
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're 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 don't 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 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 . 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.as
Further Information
Get more info on 'Oligodendrocyte'.
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