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myelin sheath
myelin sheath (medullary sheath) The layer of fatty material that surrounds and electrically insulates the axons of most vertebrate and some invertebrate neurons. The myelin sheath enables a more rapid transmission of nerve impulses (at speeds up to 120 m s–1). It consists of layers of membrane derived from Schwann cells. The sheath is interrupted at intervals along the axon by nodes of Ranvier; myelinated sections of axon are called internodes.
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"myelin sheath." A Dictionary of Biology. 2004. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "myelin sheath." A Dictionary of Biology. 2004. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O6-myelinsheath.html "myelin sheath." A Dictionary of Biology. 2004. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-myelinsheath.html |
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myelin sheath
myelin sheath (medullary sheath) A fatty sheath, composed of lipids, proteins, and polysaccharides (myelin), that surrounds and insulates the axons of neurons and permits increased current flow of nerve impulses. The myelin is produced by Schwann cells. Constrictions which occur along the sheath (nodes of Ranvier) delineate adjacent Schwann cells.
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MICHAEL ALLABY. "myelin sheath." A Dictionary of Zoology. 1999. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "myelin sheath." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O8-myelinsheath.html MICHAEL ALLABY. "myelin sheath." A Dictionary of Zoology. 1999. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-myelinsheath.html |
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