Question

Gastrula is the embryonic stage in which

• A. cleavage occurs
• B. blastocoel forms
• C. germinal layers form
• D. villi form

Answer 1

The correct option is C germinal layers form

After fertilisation, zygote is formed. It divides mitotically and formed a cell mass known as morula, which further divides and form blastula.

The blastula is a hollow sphere of cells, called blastomeres, surrounding an inner fluid-filled cavity called the blastocoele formed during an early stage of embryonic development in animals.

The blastula further divides and forms gastrula, which has two different cell masses- innner cell mass and trophoblast.

Inner cell mass has the stem cells and trophoblast forms the germinal layers ( ectoderm, mesoderm and endoderm).
Therefore, gastrula is the embryonic stage in which germinal layers forms.