Myelin is created by two distinct types of glial cells: oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS).
These cells are essential for the proper functioning of the nervous system. Myelin acts as an insulator around nerve cell axons, significantly increasing the speed at which electrical signals can travel. This process is called saltatory conduction.
Myelin-Producing Cells: A Comparison
| Cell Type | Location | Function |
|---|---|---|
| Oligodendrocytes | Central Nervous System (CNS) | Myelinates multiple axons simultaneously. |
| Schwann Cells | Peripheral Nervous System (PNS) | Myelinates a single segment of a single axon. |
Central Nervous System (CNS): Oligodendrocytes
In the brain and spinal cord (the CNS), oligodendrocytes extend their processes to wrap around the axons of neurons, forming the myelin sheath. A single oligodendrocyte can myelinate portions of multiple adjacent axons, increasing efficiency.
Peripheral Nervous System (PNS): Schwann Cells
In the nerves outside of the brain and spinal cord (the PNS), Schwann cells perform the same function of myelination. However, a key difference is that each Schwann cell only myelinates a single segment of a single axon. The gaps between the myelin sheaths, called Nodes of Ranvier, are crucial for the rapid transmission of nerve impulses.
Importance of Myelin
Myelin is vital for the rapid and efficient transmission of nerve impulses. Damage to myelin, such as in multiple sclerosis (MS), can lead to a wide range of neurological problems. Understanding the cells that create myelin and the factors that affect their function is therefore critical for developing treatments for demyelinating diseases.
In summary, both oligodendrocytes and Schwann cells contribute to the formation of myelin, but they do so in different parts of the nervous system and in different ways. Oligodendrocytes myelinate multiple axons in the CNS, while Schwann cells myelinate only a single segment of a single axon in the PNS.
