white matter


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Related to white matter: gray matter

matter

 [mat´er]
1. physical material having form and weight under ordinary conditions; called also substance.
2. pus.
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.

white mat·ter

[TA]
those regions of the brain and spinal cord that are largely or entirely composed of nerve fibers and contain few or no neuronal cell bodies or dendrites.

white matter

n.
Whitish nerve tissue, especially of the brain and spinal cord, consisting chiefly of myelinated nerve fibers.

white matter

the tissue of the central nervous system and much of the part of the cerebrum, consisting mainly of myelinated nerve fibers, but with some unmyelinated nerve fibers, embedded in a spongy network of neuroglia. It is subdivided in each half of the spinal cord into three funiculi: the anterior, the posterior, and the lateral white column. Each column subdivides into tracts that are closely associated in function. The anterior column divides into two ascending tracts and five descending tracts. The posterior column divides into two large ascending tracts, one small descending tract, and one intersegmental tract. The lateral column divides into six ascending tracts and four descending tracts. Also called white substance. Compare gray matter. See also cerebrum, spinal cord, spinal tract.

white mat·ter

(wīt mat'ĕr) [TA]
Those regions of the brain and spinal cord that are largely or entirely composed of nerve fibers and contain few or no neuronal cell bodies or dendrites.
Synonym(s): substantia alba, white substance.

white matter

Those parts of the central nervous system that appear white on section because they consist mainly of myelinated nerve fibres. Compare grey matter which consists mainly of nerve cell bodies.

white matter

the tissue of the CENTRAL NERVOUS SYSTEM, lying outside the GREY MATTER in the spinal cord but internal to grey matter in the brain of some vertebrates, and which contains the myelinated AXONS of nerves. The MYELIN SHEATHS give the tissue its white appearance.

substantia alba

; white matter central nervous system regions containing large amounts of myelin with few/no nerve cell bodies; e.g. spinal tracts with myelinated nerve fibres

white matter, white substance

the white nervous tissue, constituting the conducting portion of the brain and spinal cord, composed mostly of myelinated nerve fibers. Gray matter or substance is the term used to describe the tissues composed of unmyelinated fibers.
References in periodicals archive ?
In the largest study completed to-date on active military personnel using advanced MR imaging, the presence of white matter T2 hyper-intensities, also known as brain scars, was detected in 52% of the subjects who had suffered blast-related mTBI.
Since Epo-induced improvement of cognitive function after neonatal hyperoxia was not directly associated with preservation of white matter structures, we investigated whether amelioration of memory deficits might be linked to changes in neuronal connectivity.
First patient having weakness of both legs, had hyperintense foci at subcortical white matter in frontal, left centrum semiovale and right parieto-occipital area.
Posterior PVWM was operationally defined as the posterior half of the white matter extending along the body of the lateral ventricle.
Richard Todd, from Washington University, added the effect on the white matter was "pretty remarkable".
In addition, cases in which patients with HIV are receiving antiretroviral therapy can be followed up to determine if the patients regain white matter volume and CC thickness.
White matter lesions (WMLs) are characterized mainly by white matter hyperintensities on T2-weighted and fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) of the brain, and they are usually categorized into periventricular and subcortical lesions.
Doctors still dont know how victims ended up with the white matter changes, nor how exactly those changes might relate to their symptoms.
Magnetic resonance imaging (MRI) of the brain showed diffuse T2/fluid-attenuated inversion recovery hyperintense white matter lesions involving the right frontal, parietal and temporal lobes (Figure 1).