Practice question

Rotational cleavage describes mammalian pattern observed in eutherians where first division meridional, second division rotational with one blastomere dividing meridionally and sibling equatorially producing asymmetry early. Cell cycle slow, divisions not synchronous, compaction at eight-cell stage forms morula, differentiation into trophoblast outer and inner cell mass destined to embryo proper. Annelids and molluscs show spiral cleavage, echinoderms radial, roundworms also rotational variant but classic example remains mammals including humans, thus among options mammals exemplify rotational cleavage trait. This concept holds high importance for NEET, CBSE board, CUET and competitive examinations focusing on comparative morphology and