Schwann cell

Examples of Schwann cell in the following topics:

• Neuroglia of the Peripheral Nervous System

  • The two kinds of glia cells in the PNS, schwann cells and satellite cells, each have unique functions.
  • The PNS has two kinds of neuroglia: schwann cells and satellite cells.
  • Schwann cells provide myelination to peripheral neurons.
  • Functionally, the schwann cells are similar to oligodendrocytes of the CNS.
  • Satellite cells are small glia that surround neurons' sensory ganglia in the ANS.

• Characteristics of Nervous Tissue

  • It consists of neurons and supporting cells called neuroglia.
  • The cell body is like a factory for the neuron.
  • In the peripheral nervous system, Schwann cells are neuroglia cells that support neuronal function by increasing the speed of  impulse propagation.
  • The Schwann cells are underlain by the medullary sheath.
  • The myelin layer (concentric) surrounds the axon of a neuron, showing Schwann cells.

• Types of Nervous Tissue

  • Neuroglia are also called "glial cells."
  • Neuroglia in the CNS include astrocytes, microglial cells, ependymal cells and oligodendrocytes.
  • In the PNS, satellite cells and Schwann cells are the two kinds of neuroglia.
  • Satellite cells surround neuron cell bodies in the peripheral nervous system (PNS).
  • Schwann cells surround all nerve fibers in the peripheral nervous system and form myelin sheaths around the nerve fibers.

• Regeneration of Nerve Fibers

  • The growth of the sprouts are governed by chemotactic factors secreted from Schwann cells (neurolemmocytes).
  • Injury to the PNS immediately elicits the migration of phagocytes, Schwann cells, and macrophages to the lesion site to clear away debris such as damaged tissue.
  • The proximal axons are able to regrow as long as the cell body is intact and they have made contact with the Schwann cells in the endoneurial channel.
  • During Wallerian degeneration, Schwann cells grow in ordered columns along the endoneurial tube.
  • Also, macrophages and Schwann cells release neurotrophic factors that enhance regrowth.

• Capacity of Different Tissues for Repair

  • Neuroregeneration refers to the regrowth or repair of nervous tissue, cells, or cell products.
  • Growth is governed by factors secreted from Schwann cells.
  • Injury to the peripheral nervous system immediately elicits the migration of phagocytes, Schwann cells, and macrophages.
  • The proximal axons are able to regrow as long as the cell body is intact,\ and they have made contact with the Schwann cells in the endoneurial channel.
  • In undamaged muscle, the majority of satellite cells are quiescent; they neither differentiate nor undergo cell division.

• Classification of Nerves

  • These occur when an unmyelinated Schwann cell bundles the axons close together by surrounding them.
  • The Schwann cell keeps them from touching each other by squeezing its cytoplasm between the axons.

• Clusters of Neuronal Cell Bodies

  • Ganglia are composed mainly of neuron cell bodies (somata) and dendritic structures.
  • Satellite glial cells are a type of glial cell that line the exterior surface of neurons in the peripheral nervous system (PNS) .
  • Satellite glial cells (SGCs) also surround neuron cell bodies within ganglia.
  • They are of a similar embryological origin to Schwann cells of the PNS, as they are both derived from the neural crest of the embryo during development.
  • Satellite cells also act as protective, cushioning cells.

• Optic (II) Nerve

  • As a consequence, the fibers are covered with myelin produced by oligodendrocytes, rather than Schwann cells that are found in the peripheral nervous system.

• Specific T-Cell Roles

  • T helper cells assist the maturation of B cells and memory B cells while activating cytotoxic T cells and macrophages.
  • Differentiation into helper T cell subtypes occurs during clonal selection following T cell activation of naive T cells.
  • Cytotoxic T cells (TC cells, or CTLs) destroy virus-infected cells and tumor cells, and cause much of the damage in in transplant rejection and autoimmune diseases.
  • Memory T cells comprise two subtypes: central memory T cells (TCM cells) and effector memory T cells (TEM cells), which have different properties and release different cytokines.
  • Regulatory T cells (Treg cells), also known as suppressor T cells, are crucial for the maintenance of immunological tolerance.

• Natural Killer Cells

  • The role of NK cells is similar to that of cytotoxic T cells in the adaptive immune response.
  • NK cells provide rapid responses to virus-infected cells and respond to tumor formation by destroying abnormal and infected cells.
  • NK cells use wo cytolytic granule-mediated apoptosis to destroy abnormal and infected cells.
  • Virus-infected cells destroyed by cell lysis release their replicated virus particles into the body, which infects other cells.
  • Cells that are osponized with antibodies are easier for NK cells to detect and destroy.