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1. physical material having form and weight under ordinary conditions; called also substance.
gray matter areas of the nervous system where the nerve fibers are unmyelinated (not enveloped by a myelin sheath); it contains the bodies of the nerve cells. Tissue composed of myelinated fibers is called white matter. The cerebral cortex is entirely composed of gray matter and the cerebellum also contains some deep-seated masses of it. The spinal cord has a central core of gray matter surrounded by white matter; in cross section, its gray matter is shaped approximately like the letter H. Called also substantia grisea and gray substance.
white matter areas of the nervous system composed mostly of myelinated nerve fibers (those having myelin sheaths) constituting the conducting portion of the brain and spinal cord. Tissue composed of unmyelinated fibers is called gray matter. Called also substantia alba and white substance.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
[L. substantia, essence, material, fr. sub- sto, to stand under, be present]
Farlex Partner Medical Dictionary © Farlex 2012
1. A specific type of substance.
2. Discharge or waste, such as pus or feces, from a living organism.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
Material substance that occupies cavities.
Material substance that occupies space.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
matterAnatomy Stuff that occupies cavities. See Gray matter, White matter.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
[L. substantia, essence, material, fr. sub-sto, to stand under, be present]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
matterthat which constitutes the substance of physical forms, has mass, occupies space and can be quantified.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005