from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A white fatty material, composed chiefly of lipids and lipoproteins, that encloses certain axons and nerve fibers. Also called medulla.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A white, fatty material, composed of lipids and lipoproteins, that surrounds the axons of nerves.

from the GNU version of the Collaborative International Dictionary of English

  • n. A soft white substance constituting the medullary sheaths of nerve fibers, and composed mainly of cholesterin, lecithin, cerebrin, protein, and some fat.
  • n. One of a group of phosphorized principles occurring in nerve tissue, both in the brain and nerve fibers.

from The Century Dictionary and Cyclopedia

  • Resembling myelin: said of lecithin which has been placed in water and has become swollen and pasty. On microscopical examination it will then be seen to exist in the form of peculiar slimy droplets and threads, which are known as the myelin forms of the substance.
  • n. In anatomy, the white substance of Schwann, or medullary sheath of a nerve.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers


from Wiktionary, Creative Commons Attribution/Share-Alike License

From Ancient Greek μυελός (myelos, "marrow") + -in


  • For the first time researchers at the Krembil Neuroscience Centre, Toronto Western Hospital have successfully transplanted adult spinal cord stem cells into mice and rats to produce the protective cover, known as myelin, which is necessary to insulate the nerves in the central nervous system.

    Health News from Medical News Today

  • They have also been trying to figure out why the patients with multiple sclerosis lose the protective coating, called myelin, surrounding their axons, the part of the nerve cell that conducts electrical impulses.

    A New Target in Fighting Brain Disease: Metals

  • David Van Essen Washington University scientists use MRI scanning of a substance called myelin to find brain-cell branches.

    Probing the Brain's Mysteries

  • Geron's drug contains living cells, called oligodendrocyte progenitor cells, that help restore nerve fibers and myelin, which is a protective sheath that protects nerves in the central nervous system.

    FDA Clears Geron to Resume Stem-Cell Study

  • Multiple sclerosis is generally believed to be an autoimmune disease in which the patient's own cells attack the insulation, called myelin sheath, that surrounds nerves.

    New Insight Into Multiple-Sclerosis Treatment

  • Some axons are wrapped in a multi-layer coating, known as the myelin sheath, which helps insulate the axon from other axons, surrounding tissues and fluids and prevents the electrical charge from escaping from the axon.


  • Catching CTS early is critical, because if left untreated the inflamed tendons can wear down the outside coating of the nerve, called the myelin sheath.

    Writer Unboxed » Blog Archive » Wellness for Writerly Wrists

  • The scientists hope the approach, which generated a new fatty cover for the spinal cord cells called the myelin sheath, also could be shown to work in people.

    Stem Cells help Regrow Rat’s severed Spinal Cord | Impact Lab

  • In MS, a protective nerve-fiber coating called myelin comes under attack.

    Study links MS to mononucleosis virus | Impact Lab

  • Nerves that must stimulate organs requiring rapid response—for example, those that might signal the need to remove a finger from a hot surface, or power a leg muscle to run from a hungry lion—are electrically insulated by a fatty molecular layer, a nonconducting lipid sheath known as myelin.



Log in or sign up to get involved in the conversation. It's quick and easy.