Supporting cells in the central nervous system.

In the central nervous system, there are four types of supporting cells.

1. Oligodendrocytes.

The axons of many neurons are insulated by a myelin sheath, which increases the rate at which an axon can conduct an action potential.

In multiple sclerosis, the myelin sheaths in the CNS are destroyed, and action potentials are slowed.

Myelin is formed by oligodendrocytes in the CNS, (and by Schwann cells. in the PNS). Oligodendrocytes myelinate several axons from different nerves (up to around 50).

2. Microglia

These types of cell are less common. They have a role in immune defence and become phagocytic in response to infections or tissue damage.

3. Astrocyte

These cells are the most common type of supporting cell. They are involved in metabolic exchange between neurons and blood.

4. Ependymal cells. These cells line the vetricles and spinal canal.
They have cilia on their luminal surface.

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  This diagram shows a schematic arrangement of neurons and the four types of supporting cell in the central nervous system. All of these cells are found in the grey matter of the spinal cord.

• They are quite difficult to recognise in H&E sections, as you can see here, where only astrocytes can reliably be identified.

  

Peripheral nervous system

In the peripheral nervous system, there is one type of supporting cell, the Schwann cell.

Find out more about Schwann cells and the peripheral nervous system.