| pulmonary wedge pressure | The blood pressure as recorded after wedging a catheter in a small pulmonary artery; believed to reflect the pressure in the pulmonary capillaries. (12 Dec 1998) |
|---|---|
| quartz wedge | <microscopy> A compensator consisting of a gradual wedge of quartz of such orientation and dimensions as to show at least several orders of retardation colours as illustrated by the Michel Levy scale of retardation colours and birefringence vs. Thickness of specimen. The Babinet compensator employs two opposing quartz wedges, calibrated in terms of retardation. (05 Aug 1998) |
| ovarian wedge resection | <gynaecology, procedure> The surgical removal of a portion of a polycystic ovary to induce ovulation. (05 Jan 1998) |
| anterior gray column | The central gray matter of the spinal cord surrounding the central canal. Synonym: substantia intermedia centralis et lateralis, anterior gray column, Stilling's gelatinous substance, substantia gelatinosa centralis. (05 Mar 2000) |
| matter, gray | The cortex of the brain which contains nerve cell bodies. The gray matter is as opposed 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. 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) |
| central gray substance | In general: the predominantly small-celled gray matter adjoining or surrounding the central canal of the spinal cord and the third and fourth ventricles of the brainstem, in particular: the thick sleeve of gray matter surrounding the cerebral sylvian aqueduct in the midbrain, rostrally continuous with the posterior nucleus of the hypothalamus; in sections stained for myelin it stands out from the adjoining tectum and tegmentum by the poverty of its myelinated fibres. Synonym: substantia grisea centralis. (05 Mar 2000) |
| periaqueductal gray | Central gray matter surrounding the cerebral aqueduct in the mesencephalon. Physiologically it is probably involved in rage reactions, the lordosis reflex, feeding responses, bladder tonus, and pain. (12 Dec 1998) |
| Gray | <radiobiology, unit> The new international system unit (SI unit) of absorbed dose of radiation (Gy), 1 Gy = 1 J kg-1 = 100 rad. (16 Dec 1997) |
| gray cataract | A cataract of gray colour, usually seen in senile, mature, or cortical cataract. (05 Mar 2000) |
| gray collie syndrome | An autosomal recessive, inherited immunodeficiency of gray collie dogs characterised by overwhelming recurrent bacterial infections, bleeding, and coat colour dilution. Synonym: gray collie syndrome. (05 Mar 2000) |
| gray columns | The three somewhat ridge-shaped masses of gray matter (anterior, posterior, and lateral columns) that extend longitudinally through the centre of each lateral half of the spinal cord; in transverse sections these columns appear as gray horns and are therefore commonly called ventral or anterior, dorsal or posterior, and lateral horn, respectively. Synonym: columnae griseae. (05 Mar 2000) |
| gray degeneration | Degeneration of the white substance of the spinal cord, the fibres of which lose their myelin sheaths and become darker in colour. (05 Mar 2000) |
| gray fibres | A fibre having no myelin covering (CNS); a naked axon; in the PNS represented by all axons lying in troughs in a single Schwann cell (Schwann cell unit); a slow conducting fibre. Synonym: gray fibres, nonmedullated fibres, Remak's fibres. (05 Mar 2000) |
| gray hepatisation | The second stage of hepatisation in pneumonia, when the exudate is beginning to degenerate prior to breaking down; the colour is a yellowish gray or mottled. (05 Mar 2000) |
| gray induration | A condition occurring in lungs during and after pneumonic processes in which there is failure of resolution; there is a conspicuous increase in fibrous connective tissue in the walls of the alveoli, and also within the alveoli (e.g., fibrous organization of exudate); in contrast to brown induration, there is usually not a prominent degree of pigmentation, unless chronic passive congestion is also present. (05 Mar 2000) |