Nonmyelinating Schwann cell

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The nonmyelinating Schwann cells are a subgroup of the Schwann cells characterized by not forming myelin. [1]

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The group of nonmyelinating Schwann cells includes the terminal Schwann cells, present at neuromuscular junctions, the Schwann cells of Remak fibers (also called Remak Schwann cells) and the Schwann cells associated to sensory structures, like tactile corpuscles and lamellar corpuscles. [1]

Remak Schwann cells

The Schwann cells of Remak fibers, or Remak Schwann cells (RSCs), are named after the German neurobiologist Robert Remak and are present in nerve fibers observed by him around 1838. In the peripheral nervous system, the Remak Schwann cells are more numerous than the myelinating Schwann cells. [1]

They provide metabolic support to neurons, among other functions, but as no specific genetic markers have been detailed (at least as of 2017), there is still a large gap in understanding their biology in separation of other Schwann cells. [2]

Terminal Schwann cells

Terminal Schwann cells (tSCs), also called perisynaptic Schwann cells,” and “teloglia", are nonmyelinating Schwann cells present at neuromuscular junctions. It is suggested that they might play a role in forming and maintaining synapses or modulating synaptic signalling. [1] [3]

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<span class="mw-page-title-main">Myelin</span> Fatty substance that surrounds nerve cell axons to insulate them and increase transmission speed

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Wallerian degeneration is an active process of degeneration that results when a nerve fiber is cut or crushed and the part of the axon distal to the injury degenerates. A related process of dying back or retrograde degeneration known as 'Wallerian-like degeneration' occurs in many neurodegenerative diseases, especially those where axonal transport is impaired such as ALS and Alzheimer's disease. Primary culture studies suggest that a failure to deliver sufficient quantities of the essential axonal protein NMNAT2 is a key initiating event.

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<span class="mw-page-title-main">Neuron doctrine</span>

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<span class="mw-page-title-main">Axon terminal</span> Nerve fiber part

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Perisynaptic schwann cells are neuroglia found at the Neuromuscular junction (NMJ) with known functions in synaptic transmission, synaptogenesis, and nerve regeneration. These cells share a common ancestor with both Myelinating and Non-Myelinating Schwann Cells called Neural Crest cells. Perisynaptic Schwann Cells (PSCs) contribute to the tripartite synapse organization in combination with the pre-synaptic nerve and the post-synaptic muscle fiber. PSCs are considered to be the glial component of the Neuromuscular Junction (NMJ) and have a similar functionality to that of Astrocytes in the Central Nervous System. The characteristics of PSCs are based on both external synaptic properties and internal glial properties, where the internal characteristics of PSCs develop based on the associated synapse, for example: the PSCs of a fast-twitch muscle fiber differ from the PSCs of a slow-twitch muscle fiber even when removed from their natural synaptic environment. PSCs of fast-twitch muscle fibers have higher Calcium levels in response to synapse innervation when compared to slow-twitch PSCs. This balance between external and internal influences creates a range of PSCs that are present in the many Neuromuscular Junctions of the Peripheral Nervous System.

<span class="mw-page-title-main">Tripartite synapse</span>

Tripartite synapse refers to the functional integration and physical proximity of:

References

  1. 1 2 3 4 Griffin JW, Thompson WJ (November 2008). "Biology and pathology of nonmyelinating Schwann cells". Glia. 56 (14): 1518–1531. doi:10.1002/glia.20778. PMID   18803315.
  2. Harty BL, Monk KR (December 2017). "Unwrapping the unappreciated: recent progress in Remak Schwann cell biology". Current Opinion in Neurobiology. 47: 131–137. doi:10.1016/j.conb.2017.10.003. PMC   5963510 . PMID   29096241.
  3. Feng Z, Ko CP (September 2008). "Schwann cells promote synaptogenesis at the neuromuscular junction via transforming growth factor-beta1". The Journal of Neuroscience. 28 (39): 9599–9609. doi:10.1523/JNEUROSCI.2589-08.2008. PMC   3844879 . PMID   18815246.