| aquaphobia | <psychology> Morbid fear of water. Origin: L. Aqua, water, + G. Phobos, fear (05 Mar 2000) |
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| aquaporin | <protein> Plant cell wall polysaccharides containing predominantly arabinose and galactose. Two main types are recognised: arabinogalactan 1, found in the pectin portion of angiosperms and containing _(1-4) linked galactan and _ arabinose side chains, arabinogalactan II, a highly branched polymer containing _(1-3) and _ (1-6) linked galactose and peripheral _ arabinose residues. Arabinogalactan II is found in large amounts on some gymnosperms, especially larches and is related to AGP. (18 Nov 1997) |
| aquapuncture | <medicine> The introduction of water subcutaneously for the relief of pain. Origin: L. Aqua water, + punctura puncture, pungere, punctum, to, prick. Source: Websters Dictionary (01 Mar 1998) |
| aquarium | An artificial pond, or a globe or tank (usually with glass sides), in which living specimens of aquatic animals or plants are kept. Origin: L. See Aquarius, Ewer. Source: Websters Dictionary (01 Mar 1998) |
| aquarius | <astronomy> The Water-bearer; the eleventh sign in the zodiac, which the sun enters about the 20th of January; so called from the rains which prevail at that season in Italy and the East. A constellation south of Pegasus. Origin: L. Aquarius, adj, relating to water, and n, a water-carrier, fr. Aqua. See Aqua. Source: Websters Dictionary (01 Mar 1998) |
| Aquaspirillum | A genus of motile, nonsporeforming, aerobic bacteria (family Spirillaceae) containing Gram-negative, rigid, helical or helically curved cells which are 0.2 to 1.5 um in diameter. Motile cells contain fascicles of flagella at one or both poles. Some species can grow anaerobically with nitrate instead of oxygen as the terminal electron acceptor. These organisms are chemoorganotrophic, possessing a strictly respiratory metabolism. They do not ferment carbohydrates; a few species can oxidise a limited variety of carbohydrates. The habitat of these organisms is fresh water. The type species is Aquaspirillum serpens. Origin: L. Aqua, water, + spirillum, coil (05 Mar 2000) |
| aquatic | <ecology, marine biology> Living in or on water for all or a substantial part of the life span (generally restricted to fresh water or inland waters). (09 Oct 1997) |
| aquatic plant | <botany> Plants that must grow in water whether rooted in the mud or floating without anchorage, plants that must complete part or all of their life cycle in or near the water. (09 Oct 1997) |
| aquatic root | <plant biology> Roots that develop on stems above the normal position occupied by roots, in response to prolonged inundation with water. (09 Oct 1997) |
| aqueduct | 1. A conductor, conduit, or artificial channel for conveying water, especially one for supplying large cities with water. The term is also applied to a structure (similar to the ancient aqueducts), for conveying a canal over a river or hollow; more properly called an aqueduct bridge. 2. <anatomy> A canal or passage; as, the aqueduct of Sylvius, a channel connecting the third and fourth ventricles of the brain. Origin: F. Aqueduc, OF. Aqueduct (Cotgr), fr. L. Aquaeductus; aquae, gen. Of aqua water + ductus a leading, ducere to lead. See Aqua, Duke. Source: Websters Dictionary (01 Mar 1998) |
| aqueduct of cerebrum | An ependymal-lined canal in the mesencephalon about 20 mm long, connecting the third to the fourth ventricle. Synonym: aqueductus cerebri, aqueduct of cerebrum, aqueductus sylvii, iter a tertio ad quartum ventriculum, sylvian aqueduct. (05 Mar 2000) |
| aqueduct of sylvius | A canal between two of the cavities (called the third and fourth ventricles) in the brain through which cerebrospinal fluid passes. (12 Dec 1998) |
| aqueduct veil | A membrane obstructing the sylvian aqueduct, causing a noncommunicating hydrocephalus. (05 Mar 2000) |
| aqueductal intubation | Insertion of a tube in the sylvian aqueduct to relieve atresia or narrowing of the aqueduct. (05 Mar 2000) |
| aqueductal stenosis | <radiology> most common cause of congenital hydrocephalus (43%), aqueduct develops about the 6th week of gestation, M:F = 2:1, other congenital anomalies (16%): thumb deformities, prognosis: 11-30% mortality aetiology: infectious (50%): toxoplasmosis, CMV, syphillis, mumps, influenza, developmental: forking, narrowing, transverse septum (X-linked recessive), neoplastic (extremely rare): glioma, pinealoma, meningioma (12 Dec 1998) |