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Encyclopedia > Schwann cell

Named after the German physiologist Theodor Schwann, Schwann cells are a variety of neuroglia that mainly provide myelin insulation to axons in the peripheral nervous system of jawed vertebrates. The vertebrate nervous system relies on this myelin sheath for insulation and as a method of decreasing membrane capacitance in the axon, thus allowing for saltatory conduction to occur and for an increase in impulse speed, without an increase in axonal diameter. Non-myelinating Schwann cells are involved in maintenance of axons and are crucial for neuronal survival. Some group around smaller axons and form Remak bundles. Schwann cells are the peripheral nervous system's analogues of the central nervous system oligodendrocytes. File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Theodore Schwann Theodor Schwann (December 7, 1810 in Neuss, Prussia - January 11, 1882, in Cologne) was a German physiologist, histologist and cytologist. ... Neuroglia cells of the brain shown by Golgis method. ... In neuroscience, myelin is an electrically insulating phospholipid layer that surrounds the axons of many neurons. ... An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... The peripheral nervous system or PNS, is part of the nervous system, and consists of the nerves and neurons that reside or extend outside the central nervous system (the brain and spinal cord) to serve the limbs and organs, for example. ... A diagram showing the CNS: 1. ... These are a variety of neuroglias that wrap around neurons in Central Nervous System to for the mtolin sheath, increasing impulse speed. ...


Schwann cells begin to form the myelin sheath in mammals during fetal development and work by spiraling around the axon, sometimes with as many as 100 revolutions. A well-developed Schwann cell is shaped like a rolled-up sheet of paper, with layers of myelin in between each coil. The inner layers of the wrapping, which are predominantly membrane material, form the myelin sheath while the outermost layer of nucleated cytoplasm forms the neurolemma. Only a small volume of residual cytoplasm communicates the inner from the outer layers. This is seen histologically as the Schmidt-Lantermann Incisure. Since each Schwann cell can cover about a millimeter (0.04 inches) along the axon, hundreds and often thousands are needed to completely cover an axon, which can sometimes span the length of a body. The gaps between the Schwann cell covered segments are the Nodes of Ranvier, important sites of ionic and other exchanges of the axon with the extracellular liquid. Unlike oligodendrocytes, myelinating Schwann cells provide insulation to only one axon (see image). This arrangement permits saltatory conduction of action potentials which greatly speeds it and saves energy. In neuroscience, myelin is an electrically insulating phospholipid layer that surrounds the axons of many neurons. ... Illustration of a lipid bilayer A cell membrane, plasma membrane or plasmalemma is a selectively permeable lipid bilayer coated by proteins which comprises the outer layer of a cell. ... Organelles. ... Neurolemma (spelled also neurolema, neurilemma and neurilema, and used interchangeably with epineurium) is the insulating myelin layer that surrounds an individual peripheral nerve fiber. ... Oblique clefts may be seen in the medullary sheath, subdividing it into irregular portions, which are termed Schmidt-Lanterman incisures (or clefts of schmidt-lanterman, segments of Lantermann, medullary segments. ... Conversion of units refers to conversion factors between units of measurement. ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ... This article is about Anatomy, for the musical group see Nodes of Ranvier (band) Nodes of Ranvier are regularly spaced gaps in the myelin sheath around an axon or nerve fiber. ... These are a variety of neuroglias that wrap around neurons in Central Nervous System to for the mtolin sheath, increasing impulse speed. ... Saltatory conduction is a means by which action potentials are transmitted along myelinated nerve fibers. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ...


A number of experimental studies since 2001 have implanted Schwann cells in an attempt to induce remyelination in multiple sclerosis-afflicted patients.[1]


The name Schwann is also shared by Schwann Hawtwynn, a famous resident of Lower Sackville.


Histology

Schwann cells appear under a light microscope when immunostained with an anti-S-100 antibody ([2]


External links

  • Diagram at clc.uc.edu
  • Histology at BU 21301loa - "Ultrastructure of the Cell: myelinated axon and Schwann cell"

Robert O. Becker wrote The Body Electric, which describes how the Schwann Cell network describes the acupuncture meridians. For the unrelated Jesuit university in Chestnut Hill, see Boston College. ...

Nervous tissue - edit
Neurons (gray matter): soma, axon (axon hillock, axoplasm, axolemma, neurofibril/neurofilament), dendrite (Nissl body, dendritic spine)
types (bipolar, pseudounipolar, multipolar, pyramidal, Purkinje, Renshaw, granule)

Synapses: neuropil, boutons, synaptic vesicle, neuromuscular junction, electrical synapse Nervous tissue is the fourth major class of vertebrate tissue. ... Drawing by Santiago Ramón y Cajal of neurons in the pigeon cerebellum. ... Grey matter is a category of nervous tissue with many nerve cell bodies and few myelinated axons. ... The soma is the bulbous end of a neuron, containing the nucleus. ... An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... The axon hillock is the anotomical part of a neuron that connects the cell body to the axon. ... Axoplasm is the cytoplasm of the axon of a neuron. ... The axolemma is the membrane of a neurons axon. ... Intermediate filaments are one component of the cytoskeleton - important structural components of living cells. ... The term Dendrite stems from the Greek word dendron (literally “tree”), and typically refers to the branched projections of a neuron that act to conduct the electrical stimulation received from other cells to and from the cell body, or soma of the neuron from which the dendrites project. ... Image of a Nissl-stained histological section through the rodent hippocampus showing various classes of neurons. ... Close up of the dendrite of a striatal medium spiny neuron. ... As a part of the retina, the bipolar cell exists between photoreceptors (rod cells and cone cells) and ganglion cells. ... Pseudounipolar cells (Pseudo- false, uni- one) are sensory neurons in the peripheral nervous system. ... The multipolar neuron possesses a single (usually long) axon and many dendrites, allowing for the integration of a great deal of information from other neurons. ... A pyramidal cell is a multipolar neuron located in the hippocampus and cerebral cortex. ... Drawing of pigeon Purkinje cells (A) by Santiago Ramon y Cajal Purkinje cells are a class of GABAergic neuron located in the cerebellar cortex. ... Renshaw cells are located in the spinal cord horn. ... In neuroscience, granule cells are tiny cells found within the granular layer of the cerebellum. ... Illustration of the major elements in a prototypical synapse. ... Neuropil is the feltwork of unmyelinated neuronal processes (axonal and dendritic) within the gray matter of the central nervous system Traditionally, when pathologists looked at brain tissue they concentrated on neurons (the active functioning cells of the brain), glial cells and axons (especially in white matter, which is mostly composed... In a synapse, a bouton (or synaptic button, or presynaptic button) is a protuberance at the pre-synaptic nerve terminal where two axons connect with each other. ... In a neuron, synaptic vesicles, also called neurotransmitter vesicles, store the various neurotransmitters that are released during calcium-regulated exocytosis at the presynaptic terminal into the synaptic cleft of a synapse. ... A neuromuscular junction is the junction of the axon terminal of a motoneuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscles surface. ... An electrical synapse is a mechanical and electrically conductive link between two abutting neurons that is formed at a narrow gap between the pre- and postsynaptic cells known as a gap junction. ...


Sensory receptors: Free nerve ending, Meissner's corpuscle, Merkel nerve ending, Muscle spindle, Pacinian corpuscle, Ruffini ending, Olfactory receptor neuron, Photoreceptor, Hair cell, Taste bud In a sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of an organism. ... NERVE ENDINGS SUCK PENIS!!! ... Meissners corpuscles (discovered by the anatomist Georg Meissner (1829-1903) are a type of mechanoreceptor and more specifically, a tactile corpuscle(corpusculum tactus). ... Merkel nerve endings are mechanoreceptors found in the skin and mucosa of vertebrates that provide touch information to the brain. ... A muscle spindle is a specialized muscle structure innervated by both sensory and motor neuron axons. ... A Pacinian corpuscle is a structure that functions as a mechanoreceptor. ... Ruffini Endings are one of the four main cutaneous mechanoreceptors. ... An olfactory receptor neuron, also called an olfactory sensory neuron, is the primary transduction cell for olfaction in the olfactory system. ... A photoreceptor is a specialized form of cell (specifically, neuron) that is capable of phototransduction. ... Hair cells are the sensory cells of both the auditory system and the vestibular system in all vertebrates. ... Taste buds are small structures on the upper surface of the tongue, soft palate, and epiglottis that provide information about the taste of food being eaten. ...


Glial cells: astrocyte, ependymal cells, microglia, radial glia This article or section does not cite its references or sources. ... Astrocytes, also known as astroglia, are characteristic star-shaped glial cells in the brain. ... It has been suggested that this article or section be merged with Ependyma. ... Microglia are a type of glial cell that act as the immune cells of the Central nervous system (CNS). ... Radial glial cells are a pivotal cell type in the developing CNS involved in key developmental processes, ranging from patterning and neuronal migration to their newly described role as precursors during neurogenesis. ...


Myelination (white matter): Schwann cell, oligodendrocyte, nodes of Ranvier, internode, Schmidt-Lanterman incisures, neurolemma In neuroscience, myelin is an electrically insulating phospholipid layer that surrounds the axons of many neurons. ... White matter is one of the two main solid components of the central nervous system. ... Oligodendrocytes (from Greek literally meaning few tree cells), or oligodendroglia (Greek, few tree glue)[1], are a variety of neuroglia. ... This article is about Anatomy, for the musical group see Nodes of Ranvier (band) Nodes of Ranvier are regularly spaced gaps in the myelin sheath around an axon or nerve fiber. ... The portion of nerve fiber between two Nodes of Ranvier is called an internodal segment (or internode). ... Oblique clefts may be seen in the medullary sheath, subdividing it into irregular portions, which are termed Schmidt-Lanterman incisures (or clefts of schmidt-lanterman, segments of Lantermann, medullary segments. ... Neurolemma (spelled also neurolema, neurilemma and neurilema, and used interchangeably with epineurium) is the insulating myelin layer that surrounds an individual peripheral nerve fiber. ...


closely related Connective tissue: epineurium, perineurium, endoneurium, nerve fascicle, meninges In the human body there are four types of tissue: (1) Epithelial, (2) Connective, (3) Muscle, and (4) Nervous Tissue. ... Neurolemma (spelled also neurolema, neurilemma and neurilema, and used interchangeably with epineurium) is the insulating myelin layer that surrounds an individual peripheral nerve fiber. ... In a nerve fiber, the tubular sheath of the funiculi, perineurium, is a fine, smooth, transparent membrane, which may be easily separated, in the form of a tube, from the fibers it encloses; in structure it is made up of connective tissue, which has a distinctly lamellar arrangement. ... The nerve fibers are held together and supported within the funiculus by delicate connective tissue, called the endoneurium. ... A small bundle of fibers, enclosed in a tubular sheath, is called a funiculus; if the nerve is of small size, it may consist only of a single funiculus; but if large, the funiculi are collected together into larger bundles or nerve fascicles, which are bound together in a common... The meninges (singular meninx) are the system of membranes that envelop the central nervous system. ...


  Results from FactBites:
 
Schwann cell - definition of Schwann cell - Labor Law Talk Dictionary (215 words)
Schwann cells are a variety of neuroglia that wrap around axons in the peripheral nervous system, forming the myelin sheath.
Schwann cells begin to form the myelin sheath in mammals during fetal development and work by spiraling around the axon, sometimes with as many as 100 revolutions.
Since each Schwann cell can cover about a millimeter (0.04 inches) along the axon, hundreds and often thousands are needed to completely cover an axon, which can sometimes span the length of a body.
Theodor Schwann (1810-1882) (300 words)
Theodor Schwann, a German cytologist and physiologist, was born in Neuss, Germany on December 7, 1810.
Schwann became professor at the Belgium Universities of Louvain, in 1838, and Li├Ęge, in 1848.
Schwann coined the term "metabolism" to describe the chemical changes that take place in living tissue and formulated the basic principles of embryology by observing that an egg is a single cell that will eventually develop into a complete organism.
  More results at FactBites »

 
 

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