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Schwann cells or neurolemmocytes (named after German physiologist Theodor Schwann) are the principal glia of the peripheral nervous system (PNS). Glial cells function to support neurons and in the PNS, also include satellite cells, olfactory ensheathing cells, enteric glia and glia that reside at sensory nerve endings, such as the Pacinian corpuscle.
Neurilemma (also known as neurolemma, sheath of Schwann, or Schwann's sheath) [1] is the outermost nucleated cytoplasmic layer of Schwann cells (also called neurilemmocytes) that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system. [2]
Glial cells known as astrocytes enlarge and proliferate to form a scar and produce inhibitory molecules that inhibit regrowth of a damaged or severed axon. In the peripheral nervous system (PNS), glial cells known as Schwann cells (or also as neuri-lemmocytes) promote repair. After axonal injury, Schwann cells regress to an earlier ...
These layers are generally uniform and continuous, but due to imperfect nature of the process by which Schwann cells wrap the nerve axon, this wrapping process can sometimes leave behind small pockets of residual cytoplasm displaced to the periphery during the formation of the myelin sheath. These pockets, or "incisures", can subdivide the ...
These occur when a non-myelinating Schwann cell bundles the axons close together by surrounding them. [4] The Schwann cell keeps them from touching each other by squeezing its cytoplasm between the axons. [4] The condition of Remak bundles varies with age. [4] The number of C fiber axons in each Remak bundle varies with location. [3]
When a longitudinal section is made through a myelinating Schwann cell at the node, three distinctive segments are represented: the stereotypic internode, the paranodal region, and the node itself. In the internodal region, the Schwann cell has an outer collar of cytoplasm, a compact myelin sheath, and inner collar of cytoplasm, and the axolemma.
The cell was first discovered by Robert Hooke in 1665 using a microscope. The first cell theory is credited to the work of Theodor Schwann and Matthias Jakob Schleiden in the 1830s. In this theory the internal contents of cells were called protoplasm and described as a jelly-like
First, after a period of nerve cell injury, SGCs are known to up-regulate GFAP and to undergo cell division. They have the ability to release chemoattractants, which are analogous to those released by Schwann cells and contribute to the recruitment and proliferation of macrophages. Additionally, several research groups have found that SGC ...