micromere


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micromere

[′mī·krə‚mir]
(embryology)
A small blastomere of the upper or animal hemisphere in eggs that undergo uneven cleavage.
References in periodicals archive ?
Voronina E, Lopez M, Juliano CE, Gustafson E, Song JL (2008) Vasa protein expression is restricted to the small micromeres of the sea urchin, but is inducible in other lineages early in development.
As a rule, specification of 3D and formation of the mesentoblast occur as soon as the presumptive ectodermal micromeres and endodermal macromeres have been separated.
Micromere descendants at the blastula stage are involved in normal archenteron formation in sea urchin embryos.
3D) and subsequently in specific micromere progeny of the A and C quadrants for proper cell specification and dorsoventral (DV) axis formation in the gastropod Ilyanassa.
During cleavage, gastropod Hb-like expression is uniform and labels both micromere and macromere nuclei (Fig.
In addition, an apical sensory organ, often associated with a tuft of long cilia, arises from cells generated from the 1st micromere tier, and additional cells anterior to the mouth may bear short cilia.
The recent identification of HesC as the Repressor of Micromeres may be typical of the impact the sea urchin genome has for studies that are not directly concerned with the genome.
For example, patellogastropods (true limpets) and euthyneuran gastropods (pulmonates and opisthobranchs) with equally cleaving eggs depend on regional segregation of morphogenetic determinants to specify the animal-vegetal axis (4), but an inductive interaction between micromeres and one of the macromeres later specifies the dorsoventral axis of the embryo (5, 6).
Micromere differentiation in the sea urchin embryo: immunochemical characterization of primary mesenchyme cell-specific antigen and its biological roles.
Development of a "primitive" sea urchin (Eucidaris tribuloides): irregularities in the hyaline layer, micromeres, and primary mesenchyme.
4C), with 4 cells of macromeres at the vegetal pole (lower hemisphere) and 4 cells of micromeres at the animal pole (upper hemisphere).
1982) reported that both species Coptotermes heimi and Micromeres obesi do not penetrate Permethrin treated soil.