cleavage

cleavage
1. Series of mitotic cell divisions occurring in the ovum immediately following its fertilization. SYN: segmentation (2). SEE ALSO: c. division. 2. Splitting of a complex molecule into two or more simpler molecules. SYN: scission (2). 3. Linear clefts in the skin indicating the direction of the fibers in the dermis. SEE ALSO: tension lines, under line. 4. Midline depression or furrow between mature female breasts (common).
- abnormal c. of cardiac valve congenital malformation of a valve leaflet with a defect extending from the free margin.
- adequal c. c. resulting in the formation of blastomeres of approximately equal size.
- complete c. SYN: holoblastic c..
- determinate c. c. resulting in blastomeres each capable of developing only into a particular embryonic structure.
- discoidal c. meroblastic c. limited to the small cap (animal pole) of protoplasm of large-yolked eggs, such as the telolecithal eggs of birds.
- enamel c. the splitting of enamel in a plane parallel to the direction of the enamel rods.
- equal c. c. producing blastomeres of like size.
- equatorial c. c. in which the plane of cytoplasmic division is at right angles to the axis of the ovum.
- holoblastic c. c. in which the blastomeres are completely separated; the entire egg participates in cell division. SYN: complete c., total c..
- incomplete c. SYN: meroblastic c..
- indeterminate c. c. resulting in blastomeres of similar developmental potencies, each capable, when isolated, of producing an entire embryonic body.
- meridional c. c. in a plane through the axis of the zygote.
- meroblastic c. incomplete separation of the blastomeres, with the divisions being limited to the nonyolked portion of the egg. SYN: incomplete c..
- phosphoroclastic c. SYN: phosphorolysis.
- progressive c. in fungi, a type of sporulation in which c. planes in the cytoplasm first produce protospores and then sporangiospores in a sporangium.
- pudendal c. SYN: pudendal cleft.
- subdural c. SYN: subdural space.
- superficial c. meroblastic c. with the divisions limited to the peripheral (surface) cytoplasm of a centrolecithal egg.
- thioclastic c. the splitting of a bond in fashion analogous to hydrolysis or phosphorolysis except that the elements of a substituted hydrogen sulfide (usually coenzyme A) are added across the break.
- total c. SYN: holoblastic c..
- unequal c. c. producing blastomeres of different sizes at the two poles.

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cleav·age 'klē-vij n
1) the series of synchronized mitotic cell divisions of the fertilized egg that results in the formation of the blastomeres and changes the single-celled zygote into a multicellular embryo also one of these cell divisions
2) the splitting of a molecule into simpler molecules

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n.
(in embryology) the process of repeated cell division of the fertilized egg to form a ball of cells that becomes the blastocyst. The cells (blastomeres) do not grow between divisions and so they decrease in size.

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cleav·age (kleґvəj) 1. division into distinct parts. 2. the mitotic division of the zygote, the size of the structure remaining unchanged as the cleavage cells, or blastomeres, become smaller and smaller with each division.

Medical dictionary. 2011.

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Look at other dictionaries:

  • Cleavage — Cleav age, n. 1. The act of cleaving or splitting. [1913 Webster] 2. (Crystallog.) The quality possessed by many crystallized substances of splitting readily in one or more definite directions, in which the cohesive attraction is a minimum,… …   The Collaborative International Dictionary of English

  • Cleavage — may refer to: Cleavage (breasts), partial exposure of the separation between a woman s breasts. Cleavage enhancement, methods of making a person s breast cleavage look more substantial than it really is. Buttock cleavage, minor exposure of the… …   Wikipedia

  • cleavage — cleavage. См. дробление. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Cleavage — Cleavage. См. Расщепление. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • cleavage — index coherence, disaccord, division (act of dividing), estrangement, separation, severance, split Burton s Legal Thesaurus. Wil …   Law dictionary

  • cleavage — 1816, in geology, action of splitting (rocks or gems) along natural fissures, from CLEAVE (Cf. cleave) (1) + AGE (Cf. age). General meaning action or state of cleaving or being cleft is from 1867. The sense of cleft between a woman s breasts in… …   Etymology dictionary

  • cleavage — [n] gap break, chasm, cleft, discontinuity, divide, division, fracture, hole, rift, schism, separation, severance, split, valley; concept 513 …   New thesaurus

  • cleavage — ► NOUN 1) a sharp division; a split. 2) the cleft between a woman s breasts. 3) Biology cell division, especially of a fertilized egg cell. 4) the splitting of rocks or crystals in a preferred plane or direction …   English terms dictionary

  • cleavage — [klēv′ij] n. 1. a cleaving, splitting, or dividing 2. the manner in which a thing splits 3. a cleft; fissure; division 4. the hollow between a woman s breasts, as made visible by a low cut neckline 5. Biol. a) cell division, esp. the series of… …   English World dictionary

  • cleavage — /klee vij/, n. 1. the act of cleaving or splitting. 2. the state of being cleft. 3. the area between a woman s breasts, esp. when revealed by a low cut neckline. 4. a critical division in opinion, beliefs, interests, etc., as leading to… …   Universalium

  • Cleavage — Gesellschaftliche Konfliktlinien nach Lipset/Rokkan Die Cleavage Theorie ist eine politikwissenschaftliche Theorie in der Wahlforschung, die versucht, Wahlergebnisse in Europa anhand langfristiger Konfliktlinien in der Gesellschaft zu erklären… …   Deutsch Wikipedia

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