| germinal membrane | In many eggs with a large amount of yolk, cell division (cleavage) is restricted to a superficial layer of the fertilized egg (meroblastic cleavage). This layer is termed the blastoderm. In birds it is a flat disc of cells at one pole of the egg and in insects an outer layer of cells surrounding the yolk mass. (18 Nov 1997) |
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| paroral membrane | <biology> In ciliates the cilia in the region of the mouth may be fused into a paroral membrane. (18 Nov 1997) |
| vestibular membrane | The membrane separating the cochlear duct from the vestibular canal; it consists of squamous epithelial cells with microvilli toward the ductus, a basement membrane, and a thin layer of connective tissue toward the scala. Synonym: membrana vestibularis, paries vestibularis ductus cochlearis, Reissner's membrane, vestibular wall of cochlear duct. (05 Mar 2000) |
| glassy membrane | The basement membrane present between the stratum granulosum and the theca interna of a vesicular ovarian follicle; it becomes very prominent in large atretic follicles, the basement membrane and associated connective tissue of the hair follicle. Synonym: hyaline membrane. (05 Mar 2000) |
| virginal membrane | An obsolete term for hymen. (05 Mar 2000) |
| glial limiting membrane | A dense, resilient membrane forming the true capsule of the brain and spinal cord, composed of the processes of astrocytes (macroglia cells) and covered throughout by the pia mater, which firmly adheres to it; the two membranes are collectively called the pial-glial membrane. Synonym: membrana limitans gliae. (05 Mar 2000) |
| reissner's membrane | <anatomy> The thin membrane which separates the canal of the cochlea from the vestibular scala in the internal ear. Origin: Named from E. Reissner, A German anatomist. Source: Websters Dictionary (01 Mar 1998) |
| Payr's membrane | A fold of peritoneum that crosses over the left flexure of the colon. (05 Mar 2000) |
| cell membrane | <cell biology> The structure enveloping a cell, enclosing the cytoplasm and forming a selective permeability barrier. It consists of lipids, proteins and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees. Synonym: plasma membrane. (26 Mar 1998) |
| cell membrane permeability | A quality of cell membranes which permits the passage of solvents and solutes into and out of cells. (12 Dec 1998) |
| vitelline membrane | <cell biology> The plasma membrane of the egg. (12 Dec 1998) |
| vitreous membrane | A condensation of fine collagen fibres in places in the cortex of the vitreous body; formerly thought to form a membrane or capsule at its periphery. Synonym: lamina basalis choroideae. See: posterior limiting layer of cornea (05 Mar 2000) |
| medullary membrane | <anatomy> The layer of vascular connective tissue lining the medullary cavities of bone. Origin: NL, fr. Gr. + a bone. Source: Websters Dictionary (01 Mar 1998) |
| pemphigoid, benign mucous membrane | A chronic blistering disease with predilection for mucous membranes and less frequently the skin, and with a tendency to scarring. It is sometimes called ocular pemphigoid because of conjunctival mucous membrane involvement. (12 Dec 1998) |
| reticular membrane | The membrane formed by cuticular plates of the cells of the spiral organ of Corti; it appears netlike when viewed from above. Synonym: membrana reticularis. (05 Mar 2000) |