Question

Which of the following occurs first during the development of an embryo?

• A. Differentiation of tissues.
• B. Differentiation of organ.
• C. Differentiation of cells
• D. Differentiation of organ system.

Answer 1

The correct option is C

Differentiation of cells

The correct option is C.

Explanation of Correct option:

1. The correct sequence of development of embryo is is 'Zygote → Cleavage → Morula → Blastula → Gastrula.
2. Zygote is the aggregation of cell formed due to continuous division of cell and cell differentiation.
3. In embryology cleavage is the division of cells in the early development of the embryo, following fertilization.
4. A morul is an early-stage of embryo consisting of 16 cells which is called blastomeres and in a solid ball contained within the zona pellucida.of egg.
5. An early stage of embryonic development in animals. It is produced by cleavage of a fertilized ovum and consists of a spherical layer of around 128 cells surrounding a central fluid-filled cavity called the blastocoel.
6. Transformation of the blastocyst into gastrula with primary germ layers by rearrangement of the cells is called gastrulation.
7. So it is clear that initial condition in embryo development is cell differentiation.

Final answer:

Differentiation of cells first during the development of an embryo.