Nervous Schwann cell

The Schwann cell is the myelin-producing cell of the peripheral nervous system 16... 

The Schwann cell is the myelin-producing cell of the peripheral nervous system. When axons leave the CNS, they lose their neuroglial interrelationships and traverse a short transitional zone where they are invested by an astroglial sheath enclosed in the basal lamina of the glia limitans. The basal lamina then becomes continuous with... 

FIGURE 4-10 Myelin formation in the peripheral nervous system. (A) The Schwann cell has surrounded the axon but the external surfaces of the plasma membrane have not yet fused in the mesaxon. (B) The mesaxon has fused into a five-layered structure and spiraled once around the axon. (C) A few layers of myelin have formed but are not completely compacted. Note the cytoplasm trapped in zones where the cytoplasmic membrane surfaces have not yet fused. (D) Compact myelin showing only a few layers for the sake of clarity. Note that Schwann cell cytoplasm forms a ring both inside and outside of the sheath. (Adapted with permission from Norton, W. T. The myelin sheath. In E. S. Goldensohn and S. H. Appel (eds), Scientific Approaches to Clinical Neurology. Philadelphia Lea Febiger, 1977, pp. 259-298.)... 

The molecular and cellular events during Wallerian degeneration in the peripheral nervous system transform the damaged nerve into an environment that supports regeneration 518 Both Schwann cells and basal lamina are required for axonal regeneration... 

Stoll, G., Griffin, J. W., Li, C. Y. and Trapp, B. D. Wallerian degeneration in the peripheral nervous system participation of both Schwann cells and macrophages in myelin degradation./. Neurocytol. 18 671-683,1989. 

Oligodendrocytes are present in the CNS as well and wrap around axons to form a myelin sheath. Myelin wraps into concentric layers that spiral around the axon. Gaps in the oligodendrocytes are the nodes of Ranvier, where the membrane maintains contact with extracellular fluid. The nodes serve to propagate the action potential in myelinated axons. Schwann cells perform an analogous function, myelinating axons in the peripheral nervous system. Not all neurons are myelinated, but myelination increases the metabolic efficiency of action potentials. Demyelination of neurons produces deficits in neuronal conduction, as is seen in multiple sclerosis. 

Type XXVIII collagen belongs to the class of VWA domain-containing proteins. The primary structure is similar to type VI collagen. It is mainly a component of the basement membranes around Schwann cells in the peripheral nervous system. ... 

Fig. 1. Peripheral and central mechanism of neuropathic pain caused by vincristine. The upper diagram shows the effect of vincristine on the peripheral nervous system (comprising Schwann cells and the dorsal root ganglion (DRG)) and the involvement of interleukin (IL)-6 derived from infiltrating macrophages in neuropathic pain caused by vincristine. The lower diagram shows the effect of vincristine on the central nervous system, and the involvement of tumor necrosis factor-a (TNF-a) derived from activated microglia and astrocytes in neuropathic pain caused by vincristine.

In addition to neurons and glial cells, the nervous system contains blood vessels, fibroblasts, and other connective tissue elements. In the PNS, processes from Schwann cells that form the multilayered myelin sheaths characteristic of peripheral myelinated nerves surround most neuronal elements. 

Polyneuropathy with both sensory and motor involvement is much more common among cancer patients than pure SN [83, 110, 111]. SCLC is the most common associated tumor, although other solid tumors may be found [112]. Sensory-motor neuropathy is a quite common paraneoplastic feature in patients with onconeural antibodies, especially Hu and CRMP-5 antibodies. The CRMP-5 antibody is particularly associated with SCLC and thymoma [30]. The CRMP-5 antibody binds to oligodendrocytes as well as to neurons in specific brain regions and the retina and Schwann cells of the peripheral nervous system. In accordance with this, the clinical characteristics are heterogeneous. Many patients exhibit mixed axonal and demye-linating sensory-motor neuropathy, optic neuritis, or cerebellar dysfynction [85, 113], as well as extrapyramidal symptoms (Chapter 5.3). 

Today, with the exception of bone marrow for hematopoietic reconstitution, therapeutic cellular transplantation is an emerging technology. In recent years novel approaches in the potential restoration of function through cellular transplantation have included the use of fetal human or xenogeneic neural tissue for Parkinson s disease, ectopically implanted pancreatic islets for diabetes, Schwann cells and olfactory ensheathing glia for spinal cord injury, encapsulated chromaffin cells for pain, and various types of stem cells for the treatment of diabetes, cardiac disease, and central nervous system injuries or disease [2], There have also been trials of encapsulated cells to provide enzymes that either remove toxic products or provide activation of prodrugs to therapeutics, usually anticancer derivatives. 

The myelin sheath is one of the most abundant membrane structures in the vertebrate nervous system. It is produced by two types of glial cells, oligodendrocytes in the CNS and Schwann cells in the PNS. The myelin sheath is formed by the... 

Gillespie CS, Sherman DL, Blair GE, Brophy PJ (1994) Periaxin, a novel protein of myelinating Schwann cells with a possible role in axonal ensheathment. Neuron 12 497-508 Givogii Ml, Costa RM, Schonmann V, Silva AJ, Campagnoni AT, Bongarzone ER (2002) Central nervous system myelination in mice with deficient expression of Notch 1 receptor. J Neurosci... 

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