Question

Could embryonic development proceed normally if the first cleavage was equatorial rather than meridional? Justify your response.USE THE IMAGE PROVIDED

Cleavage in Sea Urchins Animal pole Vegetal pole cleave Animal half equatorially Mesomeres an an cleave derived an2 meridionally >an,- derived _ vegi cleave equatorially Vegetal half (unequally) veg2 micromeres stop cleaving

Answer 1

Ans. No, the cleavage will not proceed normally if the first cleavage was equatorial. As is seen in the first diagram, the spindle fibres along with chromosomes lie in the equatorial plate in anaphase state. The meridional axis divides the cell into two parts. If the plane of division would have been equatorial, the whole arrangement of spindle fibres along with chromosomes would be disrupted leading to incomplete cell division and cell death.