Macromeres

Macromeres

 

the large cells formed by complete unequal cleavage of an egg (for example, in the frog). Macromeres differ from micromeres of the same embryo in their greater size and their high content of yolk and cytoplasm.

References in periodicals archive ?
Asi, reconocen las series Macromeres, Aulacothelae y Glanduliferae.
6) M k Cladophoropsis macromeres M a,c,e,k,m Taylor (6-8,14,17,25,35,40) C.
rosaceus follows the typical pattern for echinoids with planktotrophic larvae, beginning with three equal cleavages followed by the formation of mesomeres, macromeres, and micromeres at the 16-cell stage (Fig.
4C), with 4 cells of macromeres at the vegetal pole (lower hemisphere) and 4 cells of micromeres at the animal pole (upper hemisphere).
Gray Phyllodictyon anastomosans (Harvey) Kraft & Wynne (1; C; L) Phyllodictyon pulcherrimum Gray (C; NE) Familia Siphonocladaceae Chamaedoris Montagne, 1842 Chamaedoris peniculum (Ellis & Solander) Kuntze (S y C; L y A) Cladophoropsis B0rgesen 1905 Cladophoropsis macromeres W.
Similar to the current study, dominant species reported included Sargassum polycarpum, Turbinaria tricostata, and Cladophoropsis macromeres.
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.
The first two cleavages were equal and the third unequal, producing four micromeres and four macromeres at the animal and vegetal poles, respectively (Fig.
At the third division, micromeres and macromeres could be differentiated and egg development progressed to the gastrula with cell cleavage being total, unequal and spiral (stages 6-11) (Fig.
The macromeres 4A, 4B, and 4C contribute to the stomach, the left and right midgut lobes, the style sac, and possibly the salivary glands.
Embryonic development up to the trocophore stage occurs within the egg membrane and corresponds to the typical development described for gastropod molluscs, with elimination of the two polar bodies after fertilization; segmentation is of the spiral type with the formation of micromeres and macromeres.
At the 8-cell stage, animal cells (micromeres) are larger than the vegetal macromeres, similar to all nemerteans but unlike most annelids (Shankland and Savage, 1997).