| cloacal membrane | A transitory membrane in the caudal area of the ventral wall of the embryo, separating the endodermal from the ectodermal cloaca; it is divided into anal and genitourinary membrane's that break down during the eighth to ninth week to establish the external opening for the alimentary and genitourinary tracts. (05 Mar 2000) |
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| mitochondrial membrane | The double biomembrane surrounding the mitochondrion. (05 Mar 2000) |
| Wachendorf's membrane | Remnants of the central portion of the anterior layer of the iris stroma (the iridopupillary lamina) which occludes the pupil in foetal life, and normally atrophies about the seventh month of gestation. Persistent strands usually stretch across the pupil from one iris collarette to the other, without touching the pupillary margin. Failure to regress is a rare cause of congenital blindness. Synonym: membrana pupillaris, Wachendorf's membrane. (05 Mar 2000) |
| coated pits, cell-membrane | Specialised regions of the cell membrane composed of pits coated with a bristle covering made of the protein clathrin. These pits are the entry route for macromolecules bound by cell surface receptors. The pits are then internalised into the cytoplasm to form the coated vesicles. (12 Dec 1998) |
| pial-glial membrane | The dual outer lining of the brain and spinal cord, composed of the glial limiting membrane and the pia mater. (05 Mar 2000) |
| pituitary membrane | The mucous membrane lining the nasal cavity. (12 Dec 1998) |
| placental membrane | The semipermeable layer of foetal tissue separating the maternal from the foetal blood in the placenta; composed of: 1) endothelium of the foetal vessels in the chorionic villi, 2) stromata of the villi, 3) cytotrophoblast (negligible after the fifth month of gestation), and 4) syncytial trophoblast covering the villi; the placental membrane acts as a selective membrane regulating passage of substances from the maternal to the foetal blood. Synonym: placental barrier. (05 Mar 2000) |
| complement membrane attack complex | The assembly of complement plasma glycoproteins c5b, c6, c7, c8, and polymeric c9 as a group on biological membranes. The complex forms transmembrane channels which displace lipid molecules and other constituents, thus disrupting the phospholipid bilayer of target cells leading to cell lysis by osmotic leakage. The formation of the membrane attack complex is the terminal step in the complement cascade. (12 Dec 1998) |
| plasma membrane | <cell biology> The external, limiting lipid bilayer membrane of cells. (31 Dec 1997) |
| platelet membrane glycoproteins | Surface glycoproteins on platelets which have a key role in haemostasis and thrombosis such as platelet adhesion and aggregation. Many of these are receptors. (12 Dec 1998) |
| mucous membrane | <pathology> The lubricated inner lining of the mouth, nasal passages, vagina and urethra, any membrane or lining which contains mucous secreting glands. (27 Sep 1997) |
| mucous membrane of tympanic cavity | The mucous layer of the tympanic cavity and the structures in it. Synonym: tunica mucosa cavitatis tympani, mucous membrane of tympanic cavity. (05 Mar 2000) |
| pleuropericardial membrane | A tissue fold jutting into the right or left embryonic pericardioperitoneal canal; it separates the developing pericardium from the pleural cavity and is formed by the growth of the common cardinal veins to the midline of the body. Synonym: pericardiopleural membrane, pleuropericardial membrane. (05 Mar 2000) |
| pleuroperitoneal membrane | A tissue fold jutting into the caudal portion of the embryonic pericardioperitoneal canal; it develops into the dorsal portion of the definitive diaphragm and is formed by the lungs growing caudally and the liver expanding cranially. Synonym: pleuroperitoneal membrane. (05 Mar 2000) |
| Corti's membrane | A gelatinous membrane that overlies the spiral organ (Corti) in the inner ear. Synonym: membrana tectoria ductus cochlearis, Corti's membrane, tectorium. (05 Mar 2000) |