What are swann cells?

Schwann cells are glial cells that wrap around the axons of peripheral neurons, forming a myelin sheath that insulates the axon and increases the speed of nerve impulse propagation. They are essential for the proper function of the peripheral nervous system.

Schwann cells are derived from the neural crest, which is a transient structure that forms during embryonic development. The neural crest gives rise to a variety of cell types, including neurons, glial cells, and pigment cells. Schwann cells differentiate from neural crest cells that migrate to the peripheral nervous system.

Once they reach the peripheral nervous system, Schwann cells begin to wrap around the axons of neurons. They do this by extending long, thin cytoplasmic processes that spiral around the axon. As the Schwann cell wraps around the axon, it begins to produce a myelin sheath. Myelin is a fatty substance that acts as an insulator, preventing electrical signals from leaking out of the axon.

The myelin sheath is composed of multiple layers of Schwann cell membrane. Each layer is wrapped around the axon in a spiral fashion, and the layers are held together by proteins. The myelin sheath is not continuous, but is interrupted by gaps called nodes of Ranvier. The nodes of Ranvier are important for the propagation of nerve impulses.

Schwann cells also play a role in the repair of damaged nerves. If a nerve is damaged, Schwann cells can help to regenerate the axon. They do this by secreting growth factors and by providing a scaffold for the regenerating axon to grow along.

Schwann cells are essential for the proper function of the peripheral nervous system. They provide insulation for axons, which increases the speed of nerve impulse propagation. They also play a role in the repair of damaged nerves.