| lymphocyte function-associated antigen-1 | A heterodimer molecule widely expressed on cells of haematopoietic origin. Cd11a antigen comprises the alpha chain and the CD18 antigen (antigens, CD18) the beta chain. Lfa-1 is a major receptor of T-cells, B-cells, and granulocytes. It mediates the leukocyte adhesion reactions underlying cytolytic conjugate formation, helper T-cell interactions, and antibody-dependent killing by natural killer cells and granulocytes. Intracellular adhesion molecule-1 (icam-1) has been defined as a ligand for lfa-1. (12 Dec 1998) |
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| lymphogranuloma venereum antigen | A sterile preparation of inactivated chlamydiae grown in the yolk sac of domestic fowl and used as an antigen in the Frei test. (05 Mar 2000) |
| Lyt antigen | A set of plasmalemmal surface glycoproteins on mouse T lymphocytes. Possession of Lyt 1 partly defines a T helper cell and of Lyt 2, 3 suppressor and cytotoxic cells. Formerly known as Ly antigens. See: Lyb antigen. (18 Nov 1997) |
| adamantine membrane | The primary enamel cuticle, consisting of two extremely thin layers (the inner one clear and structureless, the outer one cellular), covering the entire crown of newly erupted teeth and subsequently abraded by mastication; it is evident microscopically as an amorphous material between the attachment epithelium and the tooth. Synonym: cuticula dentis, adamantine membrane, dental cuticle, membrana adamantina, Nasmyth's cuticle, Nasmyth's membrane, skin of teeth. (05 Mar 2000) |
| allantoid membrane | An embryonic diverticulum of the hindgut of reptiles, birds, and mammals; in man its blood vessels give rise to those of the umbilical cord. (12 Dec 1998) |
| alveolocapillary membrane | The pulmonary diffusion barrier. (05 Mar 2000) |
| alveolodental membrane | <anatomy> Fibrous connective tissue surrounding the root of a tooth that separates it from and attaches it to the alveolar bone. (12 Dec 1998) |
| anal membrane | The dorsal portion of the embryonic cloacal membrane after its division by the urorectal septum. Anterior atlanto-occipital membrane, the fibrous layer that extends from the anterior arch of the atlas to the anterior margin of the foramen magnum. Synonym: membrana atlanto-occipitalis anterior. (05 Mar 2000) |
| anisotropic membrane | This type of synthetic membrane has an asymmetric pore structure: a thinfilm with tight pores backed by a thicker film with wider pores. Thistype of membrane is used for ultrafiltration andreverse osmosis, the porous side faces the feed stream and the tight-pored side faces the product stream. (09 Oct 1997) |
| anterior recess of tympanic membrane | A slitlike space on the tympanic wall between the anterior malleolar fold and the tympanic membrane. Synonym: recessus membranae tympani anterior, Troltsch's pockets, Troltsch's recesses. (05 Mar 2000) |
| anti-basement membrane antibody | Autoantibodies to renal glomerular basement membrane antigens. (05 Mar 2000) |
| anti-basement membrane glomerulonephritis | Glomerulonephritis resulting from anti-basement membrane antibodies, characterised by smooth linear deposits of IgG and C3 along glomerular capillary walls; includes rapidly progressive glomerulonephritis and glomerulonephritis in Goodpasture's syndrome. (05 Mar 2000) |
| anti-basement membrane nephritis | Glomerulonephritis produced by autologous or heterologous antibodies to the glomerular capillary basement membranes, the latter known as anti-kidney serum nephritis. (05 Mar 2000) |
| anti-glomerular basement membrane disease | Glomerulonephritis, usually of a generalised proliferative crescent-forming histologic type with a rapidly progressive course, marked by circulating anti-gbm antibodies and linear deposits of immunoglobulin and complement along the glomerular basement membrane. When associated with pulmonary haemorrhage the condition is called goodpasture syndrome. (12 Dec 1998) |
| apical plasma membrane | <cell biology> The term used for the cell membrane on the apical (inner or upper) surface of transporting epithelial cells. This region of the cell membrane is separated, in vertebrates, from the baso lateral membrane by a ring of tight junctions that prevents free mixing of membrane proteins from these two domains. (18 Nov 1997) |