Zoology - Human Reproduction Question with Solution | TestHub

Due to cleavage, the zygote is changed to a 64-celled or blastomere stage called a blastocyst, has an outer layer of trophoblast cells, inner mass of cells, and a blastocyst cavity in blastula stage. This blastocyst is going to be implanted in the endometrium of the uterus in the presence of progesterone hormone.

Formation of gastrula from blastula is known as gastrulation. During gastrulation, three primary germinal layers-ectoderm, mesoderm and endoderm are formed by morphogenetic movements and rearrangement of the cells.