A Swan cell, more accurately spelled Schwann cell, is a type of glial cell responsible for forming the myelin sheath around axons in the peripheral nervous system.
Understanding Schwann Cells
Schwann cells are essential for the proper functioning of the nervous system outside of the brain and spinal cord. They are the primary glial cells of the peripheral nervous system (PNS), analogous to oligodendrocytes in the central nervous system (CNS).
Key Features of Schwann Cells
- Myelin Formation: Schwann cells wrap around axons to create a myelin sheath, which insulates the axon and speeds up the transmission of nerve impulses.
- Single Axon Envelopment: Unlike oligodendrocytes, each Schwann cell myelinates only one segment of a single axon. According to the provided reference, "Schwann cells do not have multiple cellular extensions, but instead each cell engulfs a segment of axon and forms a multilayered myelin sheath around it."
- Location: Schwann cells are found exclusively in the PNS.
Schwann Cells vs. Oligodendrocytes
| Feature | Schwann Cells | Oligodendrocytes |
|---|---|---|
| Location | Peripheral Nervous System (PNS) | Central Nervous System (CNS) |
| Axon Envelopment | One segment of one axon | Multiple segments of multiple axons |
| Cellular Extensions | No multiple extensions | Multiple cellular extensions |
Function
Schwann cells are crucial for:
- Nerve Impulse Conduction: Myelination by Schwann cells increases the speed and efficiency of nerve impulse transmission through saltatory conduction.
- Nerve Regeneration: After nerve injury, Schwann cells can aid in the regeneration of damaged axons by creating a pathway for the axon to regrow.
