Question

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

Answer 1

In any process of development, the first thing that occurs is the differentiation of cells. Post-fertilization, the rapid mitotic divisions give rise to a blastocyst. Blastocyst gets implanted and the inner cell mass differentiates to give rise to germinal layers. Various tissues and organs are formed from the cells present in the germinal layers. So, only upon differentiation of cells, the development of tissue, organ and organ systems take place.