Oligodendrocyte
Also known as: oligodendroglia, oligodendrocytes
The myelin-forming glial cell of the CNS. Each oligodendrocyte extends several processes and myelinates one segment (internode) on each of many axons, up to ≈50.
Overview
Oligodendrocytes ("few-branched cells") have small, round, dense nuclei. In white matter they lie in rows between nerve fibres (interfascicular oligodendrocytes). In grey matter they cluster around neuronal somata as perineuronal satellite oligodendrocytes. Each extends several processes, and each process wraps a flattened sheet of membrane spirally around a segment of an axon, compacting it into myelin. One cell may myelinate internodes on up to ≈50 different axons, and conversely each axon receives segments from many oligodendrocytes. This one-to-many arrangement contrasts with the Schwann cell, which myelinates a single internode of a single axon.
CNS myelin is rich in proteolipid protein (PLP), myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG). Oligodendrocytes also supply axons with lactate through monocarboxylate transporters, which is important for axonal survival. Unlike Schwann cells, oligodendrocytes do not promote axon regeneration. Their myelin contains growth inhibitors (Nogo-A, MAG, OMgp), which, with the astroglial scar, explains the poor regeneration of CNS tracts. Oligodendrocyte precursor cells (OPCs, NG2-glia) persist in the adult and can remyelinate, although they do so incompletely in disease.
Anatomy
- Histology
Small round dark nuclei with a clear perinuclear halo ("fried-egg" appearance, a fixation artefact). They are arranged in rows in white matter and stain with Olig2.
- Development
Derived from neuroepithelial OPCs, initially from the ventral neural tube (pMN domain). CNS myelination begins in the second trimester and continues into early adulthood; the prefrontal cortex is the last region, myelinating in the 20s.
Function
- Form and maintain CNS myelin, enabling saltatory conduction in brain, spinal cord and optic nerve.
- Provide metabolic and trophic support to axons.
- Inhibit axon sprouting and regeneration, stabilising mature CNS circuits.
Clinical significance
Multiple sclerosis
Autoimmune (T- and B-cell) destruction of oligodendrocytes and CNS myelin, with plaques disseminated in time and space. Optic nerve, periventricular, corpus callosum, brainstem and cord lesions are typical. Peripheral nerves are spared, because they are myelinated by Schwann cells.
Progressive multifocal leukoencephalopathy (PML)
JC polyomavirus infects oligodendrocytes in immunosuppressed patients (AIDS, natalizumab, rituximab), causing multifocal demyelination with no enhancement or mass effect. The prognosis is poor.
Oligodendroglioma and leukodystrophies
Oligodendroglioma: a frontal-lobe adult tumour that is IDH-mutant and 1p/19q-codeleted, with fried-egg cells, "chicken-wire" capillaries and calcification. Leukodystrophies are inherited myelin disorders, for example metachromatic leukodystrophy (arylsulfatase A), Krabbe disease (galactocerebrosidase) and adrenoleukodystrophy (ABCD1, very-long-chain fatty acids). Osmotic demyelination (central pontine myelinolysis) follows over-rapid correction of hyponatraemia.
Test yourself
Which cell forms myelin in the central nervous system?
- Schwann cell
- Astrocyte
- Oligodendrocyte
- Satellite cell
Answer: Oligodendrocyte
One oligodendrocyte myelinates internodes on many CNS axons (up to ≈50). A Schwann cell myelinates a single internode of one peripheral axon. This is why MS (oligodendrocytes, CNS) and GBS (Schwann cells, PNS) affect different parts of the nervous system.
Compiled from standard anatomy and physiology references — see the Nervous System sources. For education only; not medical advice.