Cell cleavage

Related to Cell cleavage: Spiral cleavage, complete cleavage
(Biol.) multiplication of cells by fission. See Segmentation.

See also: Cleavage

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
Microtubules are the only structural constituent of the spindle apparatus required for induction of cell cleavage. J.
Wilson himself had described how chromosomes divide before cell cleavage and are united in pairs in the new cells.
the cytoplasm, which is successively partitioned during cell cleavage), so that the loss of a particular cell can mean that the cells that would descend from it, and their corresponding functions, would be entirely absent in the organism (e.g.
Hence, though the cytoskeletal structure of the ovum, and the maternal cytoplasm may produce cell cleavage and even some rudimentary differentiation, such activity is not organized, for lack of an organizer; so we could contend that no organism was ever present.
This problem, too, has its origin in the article of Bedate and Cefalo, who claim that extra-nuclear genetic information is required for the development of the embryo, so that the usual assertion that the zygote's genome possesses all the information necessary for producing a complete human being is simply not true.(25) Given that the zygote does use extragenomic material, this claim is unremarkable in itself, since in the zygote there exist extranuclear materials in its cytoplasm, derived from the mother, which cause cell cleavage. The zygote's use of this material in its cleavage and organized self-differentiation is not at all incompatible with the contention that the zygote is a biologically human organism.
We scored fertilization success using two criteria: presence of a fertilization envelope and cell cleavage. After 1 h, fertilization success was scored by examining at least the first 200 undamaged, haphazardly selected eggs on a dissecting microscope and counting the number with fertilization envelopes.
(1982) fit the fertilization data well for both indices of fertilization success (mean [R.sup.2] = 0.986 for fertilization envelopes and 0.901 for cell cleavage).
Microtubules continuously dictate distribution of actin filaments and positioning of cell cleavage in grasshopper spermatocytes.
Several recent studies have implicated Ca++ signaling in cell cleavage, particularly cytokinesis (1-4).
To shed some light on this problem, we decided to combine a number of recently developed imaging techniques to examine the variation of intracellular free Ca++ in zebrafish embryos during early cell cleavage. The major goal was to improve greatly the spatial and temporal resolution so that a more definitive Ca++ signal in association with cytokinesis could be characterized.
In the gamma-irradiated and inseminated eggs or eggs activated by the UV-irradiated spermatozoa, HHP applied at the time of prophase of the 1st zygotic division inhibits the cell cleavage which leads to duplication of the haploid set of chromosomes and production of the androgenetic and mitogynogenetic doubled haploids (DHs), respectively [7].
In the case of rainbow trout from the studied brood-stock, a three-minute HHP shock of 65.5 MPa was applied to the eggs 35 min after activation (early shock) or 350 min after activation (late shock) efficiently inhibits release of the 2nd polar body or prevents the 1st cell cleavage, respectively [15].