Glossary
Schwann Cells
What are Schwann cells?
Schwann cells are support cells in peripheral nerves, the nerves outside the brain and spinal cord. Some wrap nerve fibers, or axons, in myelin, which helps signals travel rapidly. Others support axons without forming this compact wrapping.
In the brain and spinal cord, a different cell type, the oligodendrocyte, forms myelin.
Schwann cells and the myelin sheath
A myelinating Schwann cell forms one segment of myelin around an axon. Myelin is the layered wrapping the cell produces, not a separate name for the whole cell. Non-myelinating Schwann cells can support several smaller axons without making that compact sheath.
Gaps between adjacent myelin segments are called nodes of Ranvier. These sites contain concentrated voltage-gated sodium channels. Myelin insulates the intervening axon, and action potentials are regenerated at successive nodes, supporting rapid saltatory conduction.
Ongoing support and nerve disease
Schwann cells also supply energy metabolites to axons. Their role therefore includes maintaining the axon’s working environment, not only building insulation. Demyelinating forms of Charcot–Marie–Tooth disease illustrate the importance of this relationship: abnormal peripheral myelin can slow nerve conduction and contribute to weakness and sensory problems. Different forms of this inherited disease affect different parts of the nerve.
The Schwann-cell histology review describes these signaling, support, and disease connections.
How they help after injury
Jessen and Mirsky describe how Schwann cells change after a nerve injury. They help clear damaged myelin, provide signals that support growth, and organize paths for axons to regrow.
Why it matters
Schwann cells help create the conditions for peripheral nerve repair. Regrowing an axon does not necessarily mean it reconnects correctly or restores normal function, and it is different from replacing a whole neuron.