Which of the following is common to the development of both birds and mammals?
A)holoblastic cleavage
B)epiblast and hypoblast
C)trophoblast
D)yolk plug
E)grey crescent

Question

Quizplus · Accepted Answer

Both birds and mammals undergo gastrulation, wherein the blastula develops into a structure with two distinct layers - epiblast and hypoblast. This is common to the development of both groups.

Option A (holoblastic cleavage) is a type of early cell division seen in eggs that have little or no yolk, such as those of sea urchins and frogs. This process is not common to the development of birds and mammals.

Option C (trophoblast) is a layer of cells that forms the outer layer of the blastocyst (early embryo) in mammals. Birds, however, do not have a trophoblast during development.

Option D (yolk plug) is a structure formed during gastrulation in birds, but not in mammals.

Option E (grey crescent) is a feature of amphibian eggs during the process of fertilization and cleavage, and is not present in birds or mammals.

Which of the Following Is Common to the Development of Both