Because of the crucial significance of
macromere 3D and mesentoblast 4d for the specification of the developmental fate of the embryonic cells, it may be assumed that heterochronic changes in 3D induction may have far reaching morphogenetic consequences.
The 3D
macromere serves as the organizer, and its removal at successively later stages during this time interval leads to fewer developmental defects.
During cleavage, gastropod Hb-like expression is uniform and labels both micromere and
macromere nuclei (Fig.
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).
With third cleavage, MAPK was found exclusively within the two posterior midline
macromeres. In living squid embryos, these cells undergo a delayed cleavage in comparison to the rest of the cells within the embryo.
Development of Ilyanassa following removal of the D
macromere at successive cleavage stages.
Bravo-Hollis y Sanchez-Mejorada (1991) erigieron la serie
Macromeres para ubicar a Coryphantha macromeris.
In S2, there was a differentiation of vegetative (
macromeres) and animal (micromeres) poles, while the embryo was 49.5 [+ or -] 4.7 mm in diameter.
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.
At this stage, the blastomeres divided unequally, creating cells of various sizes, including
macromeres and micromeres (Fig.
The first two cleavages were equal and the third unequal, producing four micromeres and four
macromeres at the animal and vegetal poles, respectively (Fig.