Schwann Cells

Definition

Schwann cells are specialized glial cells in the peripheral nervous system that are primarily responsible for the formation of myelin sheaths around axons. These cells play a crucial role in supporting and insulating nerve fibers, which enhances the speed of electrical impulse transmission. Their involvement in neural crest cell migration and differentiation highlights their importance in both developmental processes and nerve regeneration.

5 Must Know Facts For Your Next Test

1. Schwann cells are derived from neural crest cells during embryonic development and migrate to form myelin sheaths around peripheral neurons.
2. Unlike oligodendrocytes in the central nervous system, each Schwann cell can myelinate only one segment of a single axon, providing targeted insulation.
3. Schwann cells also play a role in nerve repair by promoting regeneration after injury through the release of growth factors and providing a supportive environment for regrowth.
4. They can differentiate into various cell types under specific conditions, including repair cells and non-myelinating support cells.
5. Disruption of Schwann cell function can lead to neurological disorders, including Charcot-Marie-Tooth disease, which affects peripheral nerve function.

Review Questions

• How do Schwann cells contribute to the process of myelination in the peripheral nervous system?
  • Schwann cells contribute to myelination by wrapping their plasma membranes around individual axons, creating a protective myelin sheath. This sheath serves to insulate the axon and speed up the conduction of electrical impulses. The process involves the extension of Schwann cell cytoplasm around the axon multiple times until layers of membrane form, resulting in efficient signal transmission along the nerve fiber.
• In what ways do Schwann cells influence the migration and differentiation of neural crest cells during development?
  • Schwann cells influence neural crest cell migration and differentiation by providing essential cues and an environment conducive to their development. As neural crest cells migrate from their origin, Schwann cells interact with them through signaling pathways that guide their fate. This interaction is vital for the proper formation of peripheral nerves, ensuring that these progenitor cells differentiate into functional neurons and glial cells.
• Evaluate the implications of Schwann cell dysfunction in peripheral nerve diseases and its potential for regeneration after injury.
  • Schwann cell dysfunction can lead to various peripheral nerve diseases, impacting signal transmission and overall nerve function. For instance, conditions like Charcot-Marie-Tooth disease highlight how impaired Schwann cell activity disrupts myelination and causes sensory and motor deficits. However, unlike central nervous system injuries, peripheral nerves have a remarkable ability to regenerate due in part to the supportive role of Schwann cells, which facilitate repair processes by releasing growth factors and guiding regenerating axons toward their targets.

Related terms

Myelin: A fatty substance that surrounds and insulates axons, allowing for faster transmission of electrical signals along nerve fibers.

Neurolemmocyte: Another name for Schwann cells, emphasizing their role in the regeneration and repair of peripheral nerves.

Neural Crest Cells: Multipotent stem cells that arise during embryonic development and give rise to a diverse range of cell types, including Schwann cells.