| gray substance | The cortex of the brain which contains nerve cell bodies. The gray matter is in contrast to the white matter, the part of the brain that contains myelinated nerve fibres. The gray matter is so named because it in fact appears gray. The white matter is white because that is the colour of myelin, the insulation covering the nerve fibres. In the mysterious affair at styles (1920), agatha christie first quoted the fictional belgian detective hercule poirot in regard to his gray matter: 'this affair must be unravelled from within.' he tapped his forehead. 'these little grey cells. It is up to them as you say over here.' (12 Dec 1998) |
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| ground substance | The amorphous material in which structural elements occur; in connective tissue, it is composed of proteoglycans, plasma constituents, metabolites, water, and ions present between cells and fibres. Synonym: substantia fundamentalis. (05 Mar 2000) |
| growth substance | <biology, cell biology> Signal molecules that are involved in the control of cell growth and differentiation. (12 Dec 1998) |
| Rolando's gelatinous substance | The apical part of the posterior horn (dorsal horn; posterior gray column) of the spinal cord's gray matter, composed largely of very small nerve cells; its gelatinous appearance is due to its very low content of myelinated nerve fibres. Synonym: substantia gelatinosa, Rolando's gelatinous substance, Rolando's substance. (05 Mar 2000) |
| chromidial substance | Endoplasmic reticulum in which ribosomal granules are applied to the cytoplasmic surface of the cisternae; involved in the synthesis and secretion of protein via membrane-bound vesicles to the extracellular space. Synonym: chromidial substance, ergastoplasm, rough-surfaced endoplasmic reticulum. (05 Mar 2000) |
| chromophil substance | The material consisting of granular endoplasmic reticulum and ribosomes that occurs in nerve cell bodies and dendrites. Synonym: basophil substance, basophilic substance, chromophil substance, Nissl bodies, Nissl granules, substantia basophilia, tigroid bodies, tigroid substance. (05 Mar 2000) |
| compact substance | The compact, noncancellous portion of bone that consists largely of concentric lamellar osteons and interstitial lamellae. Synonym: substantia compacta, compact substance, substantia compacta ossium. (05 Mar 2000) |
| white substance | <anatomy> Brain tissue composed of myelin-coated nerve cell fibres. White matter carries information between the nerve cells in the brain and spinal cord. The inner portion of the cerebrum is composed of white matter. See: grey matter. (13 Nov 1997) |
| mullerian inhibiting substance | A 535 amino acid glycoprotein secreted by the Sertoli cells of the testis. It is related to inhibin. Synonym: mullerian inhibiting factor. (05 Mar 2000) |
| muscular substance of prostate | The smooth muscle in the stroma of the prostate. Synonym: substantia muscularis prostatae, musculus prostaticus. (05 Mar 2000) |
| controlled substance | A substance subject to the Controlled Substances Act (1970), which regulates the prescribing and dispensing, as well as the manufacturing, storage, sale, or distribution of substance's assigned to five schedules according to their 1) potential for or evidence of abuse, 2) potential for psychic or physiologic dependence, 3) contributing a public health risk, 4) harmful pharmacologic effect, or 5) role as a precursor of other controlled substance's. (05 Mar 2000) |
| cortical substance | The superficial thin layer of compact bone. Synonym: substantia corticalis, cortical substance. (05 Mar 2000) |
| posterior perforated substance | The bottom of the interpeduncular fossa at the base of the midbrain, extending from the anterior border of the pons forward to the mamillary bodies, and containing numerous openings for the passage of perforating branches of the posterior cerebral arteries. Synonym: substantia perforata posterior, locus perforatus posticus, Malacarne's space. (05 Mar 2000) |
| pressor substance | One of several products of intestinal putrefaction believed to cause functional hypertension when absorbed, any alkaline substance that raises blood pressure. Synonym: pressor amine, pressor substance. (05 Mar 2000) |
| proper substance | See: substantia propria of cornea, substantia propria membranae tympani, substantia propria sclerae. (05 Mar 2000) |