| extraembryonic membrane | A structure or tissue that develops from the fertilised ovum but does not form part of the embryo proper. Synonym: embryonic membrane, extraembryonic membrane. (05 Mar 2000) |
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| false membrane | <dermatology> A thick, tough fibrinous exudate on the surface of a mucous membrane or the skin, as seen in diphtheria. Synonym: croupous membrane, neomembrane, plica, pseudomembrane. (05 Mar 2000) |
| yolk membrane | The membrane enveloping the yolk; specifically, the thickened cell membrane of large-yolked ova. Synonym: ovular membrane, vitelline membrane. Sometimes used to designate the zona pellucida of a mammalian ovum. Synonym: yolk membrane. (05 Mar 2000) |
| keratogenous membrane | The area of the corium on which the nail rests; it is extremely sensitive and presents numerous longitudinal ridges on its surface. According to some anatomists, the nail bed is the portion covered by the body of the nail, the nail matrix being only the part on which the root of the nail rests. Synonym: matrix unguis, keratogenous membrane, nail matrix, onychostroma. (05 Mar 2000) |
| umbo of tympanic membrane | The projection on the inner surface of the tympanic membrane at the end of the manubrium of the malleus; this corresponds to the most depressed point of the membrane, viewed laterally, that is commonly called the umbo. Synonym: umbo membranae tympani, umbo. (05 Mar 2000) |
| undulating membrane | Undulatory membrane, a locomotory organelle of certain flagellate (trypanosome and trichomonad) parasites, consisting of a finlike extension of the limiting membrane with the flagellar sheath; wavelike rippling of the undulating membrane produces a characteristic movement. (05 Mar 2000) |
| Zinn's membrane | The anterior layer of the iris. (05 Mar 2000) |
| unit membrane | <cell biology> The three ply, approximately 7nm wide membrane structure found in all cells, composed of a fluid lipid bilayer with intercalated proteins. The unit membrane theory carries with it the presumption that all biological membranes have basically the same structure. (18 Nov 1997) |
| fenestrated membrane | An elastic membrane, as in elastic laminae of arteries. (05 Mar 2000) |
| fertilization membrane | A viscous membrane formed on the inner surface of the vitelline membrane from the cytoplasm of the egg cell after entry of the sperm, preventing the entry of additional sperm. (05 Mar 2000) |
| fibroelastic membrane of larynx | A layer of fibrous and elastic fibres, taking the place of the submucosa in the larynx. It is divided by the laryngeal ventricle into two parts: the quadrangular membrane superiorly and the conus elasticus inferiorly. Synonym: membrana fibroelastica laryngis. (05 Mar 2000) |
| urogenital membrane | The ventral portion of the embryonic cloacal membrane after its division by the urorectal septum. (05 Mar 2000) |
| fibrous membrane | The outer fibrous part of the capsule of a synovial joint, which may in places be thickened to form capsular ligaments. Synonym: membrana fibrosa, stratum fibrosum, fibrous membrane. (05 Mar 2000) |
| urorectal membrane | In the embryo, urorectal septum separating the cloaca into urogenital sinus and rectum. Synonym: urorectal fold. (05 Mar 2000) |
| Fielding's membrane | 1. <cell biology> Layer of reflective tissue just behind the pigmented retinal epithelium of many vertebrate eyes. May consist either of a layer of guanine crystals or a layer of connective tissue. In bovine eyes reflects a blue green iridescent colour. 2. <plant biology> Layer of cells in the sporangium of a vascular plant that nourishes the developing spores. (18 Nov 1997) |