- gray m. [TA] those regions of the brain and spinal cord which are made up primarily of the cell bodies and dendrites of nerve cells rather than myelinated axons. SYN: gray substance [TA], substantia grisea [TA], substantia cinerea.
- pontine gray m. SYN: pontine nuclei, under nucleus.
- white m. [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. SYN: alba, substantia alba, white substance.
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mat·ter 'mat-ər n
1) material (as feces or urine) discharged or for discharge from the living body <an obstruction interfering with passage of \matter from the intestine>
2) material discharged by suppuration: PUS
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mat·ter (matґər) 1. anything that occupies space; substance. 2. pus.Medical dictionary. 2011.