| cleavage | <cell biology> The early divisions of the fertilized egg to form blastomeres. The cleavage pattern is radial in some phyla, spiral in others. (18 Nov 1997) |
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| cleavage cavity | The cavity in the blastula of a developing embryo. Synonym: blastocoele, cleavage cavity, segmentation cavity. Origin: blasto-+ G. Koilos, hollow (05 Mar 2000) |
| cleavage cell | One of the cells produced as the result of cell division, cleavage, in the fertilized egg. (18 Nov 1997) |
| cleavage division | The rapid mitotic division of the zygote with decrease in size of individual cells or blastomeres and the formation of a morula. See: cleavage. (05 Mar 2000) |
| cleavage lines | Lines which can be extrapolated by connecting linear openings made when a round pin is driven into the skin of a cadaver, resulting from the principal axis of orientation of the subcutaneous connective tissue (collagen) fibres of the dermis; they vary in direction with the region of the body surface. Synonym: Langer's lines. (05 Mar 2000) |
| cleavage product | A substance resulting from the splitting of a molecule into two or more simpler molecules. (05 Mar 2000) |
| cleavage site | A sequence in DNA that can be recognised and cut by a specific restriction enzyme. (12 Dec 1998) |
| cleavage spindle | The spindle formed during the cleavage of a zygote or its blastomeres. (05 Mar 2000) |
| cleavage stage, ovum | The embryo in its earliest stage, lasting from the first mitotic division of the fertilised ovum into two blastomeres to the formation of the morula, a compact mass of blastomeres. (12 Dec 1998) |
| abnormal cleavage of cardiac valve | Congenital malformation of a valve leaflet with a defect extending from the free margin. (05 Mar 2000) |
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| adequal cleavage | Cleavage resulting in the formation of blastomeres of approximately equal size. (05 Mar 2000) |
| anterior chamber cleavage syndrome | <syndrome> A congenital disorder originating from faulty separation of embryonic structures; it results in bilateral central corneal opacities, with an anterior ring attachment of the iridic pupillary border and anterior polar cataracts; associated with short-limbed dwarfism; autosomal dominant inheritance. See: iridocorneal endothelial syndrome. Synonym: Peters' anomaly. (05 Mar 2000) |
| beta-carotene cleavage enzyme | <enzyme> An enzyme catalyzing the reaction of beta-carotene plus O2 producing two retinals. Synonym: beta-carotene cleavage enzyme, carotenase, carotinase. (05 Mar 2000) |
| glycine cleavage complex | A complex of several proteins that catalyze the reversible reaction of glycine with tetrahydrofolate to produce CO2, NH3, and N5,N10-methylenetetrahydrofolate; a deficiency of this enzyme (or one of its subunits) will result in nonketotic hyperglycinaemia. Synonym: glycine synthase. (05 Mar 2000) |
| meridional cleavage | Cleavage in a plane through the axis of the zygote. (05 Mar 2000) |
| meroblastic cleavage | Incomplete separation of the blastomeres, with the divisions being limited to the nonyolked portion of the egg. Synonym: incomplete cleavage. (05 Mar 2000) |
| citrate cleavage enzyme | ATP citrate (pro-3S)-lyase |
| phosphoroclastic cleavage | <biochemistry> This reaction is an analogue to hydrolysis, except here a molecule is cleaved with phosphate as the attacking group. (09 Oct 1997) |
| complete cleavage | Cleavage in which the blastomeres are completely separated; the entire egg participates in cell division. Synonym: complete cleavage, total cleavage. (05 Mar 2000) |
| progressive cleavage | In fungi, a type of sporulation in which cleavage planes in the cytoplasm first produce protospores and then sporangiospores in a sporangium. (05 Mar 2000) |
| holoblastic cleavage | Cleavage in which the blastomeres are completely separated; the entire egg participates in cell division. Synonym: complete cleavage, total cleavage. (05 Mar 2000) |
| pudendal cleavage | The cleft between the labia majora. Synonym: rima pudendi, fissura pudendi, pudendal cleavage, pudendal slit, rima vulvae, urogenital cleft, vulvar slit. (05 Mar 2000) |
| hydrolytic cleavage | <chemistry> The splitting of a compound into fragments by the addition of water, the hydroxyl group being incorporated in one fragment and the hydrogen atom in the other. Origin: Gr. Lysis = dissolution (18 Nov 1997) |
| spiral cleavage | <marine biology> Pattern of early cleavage found in molluscs and annelids (both mosaic eggs). The animal pole blastomeres are rotated with respect to those of the vegetal pole. The handedness of the spiral twist is maternally inherited. (18 Nov 1997) |