| 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) |
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| 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) |
| aqueductus | Synonym: aqueduct. Origin: L. Fr. Aqua, water, + ductus, a leading, fr. Duco, pp. Ductus, to lead (05 Mar 2000) |
| aqueductus cerebri | 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) |
| aqueductus cochleae | A fine canal connecting the perilymphatic space of the cochlea with the subarachnoid space. Synonym: ductus perilymphaticus, aqueductus cochleae, cochlear aqueduct. (05 Mar 2000) |
| aqueductus cotunnii | aqueduct of vestibule |
| aqueductus fallopii | The bony passage in the temporal bone through which the facial nerve passes; the facial canal commences at the internal auditory meatus with the horizontal part which passes at first anteriorly (medial crus of facial canal) then turns posteriorly at the geniculum of the facial canal to pass medial to the tympanic cavity (lateral crus of facial canal); finally, it turns downward (descending part of facial canal) to reach the stylomastoid foramen. Synonym: canalis nervi facialis, aqueductus fallopii, fallopian aqueduct, fallopian canal. (05 Mar 2000) |