micromere


Also found in: Dictionary, Medical.

micromere

[′mī·krə‚mir]
(embryology)
A small blastomere of the upper or animal hemisphere in eggs that undergo uneven cleavage.
References in periodicals archive ?
[25.] 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.
In early development there is an apparent lack of a hyaline layer, irregularly arranged blastomeres, variable numbers of micromeres, and an absence of primary mesenchyme (Schroeder, 1981).
Third cleavage leads to the formation of the first quartet of micromeres located at the animal pole (1a-1d).
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.
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.
Su, et al., (1982) reported that both species Coptotermes heimi and Micromeres obesi do not penetrate Permethrin treated soil.
Eight species (Chaenactis glabriuscula, Cryptantha micromeres, C.
At this stage, the blastomeres divided unequally, creating cells of various sizes, including macromeres and micromeres (Fig.