Question

Gastrulation is a process

• A. Which begins the segregation of germ layers.
• B. That occurs just after morulation.
• C. That occur just after cleavage.
• D. Of rapid growth in blastomeres.

Answer 1

The correct option is A Which begins the segregation of germ layers.

During the process of gastrulation, the cells of the embryo undergo significant morphogenetic movements that result in the establishment of the germ layers. The layers will continue to differentiate during development to give rise to more than 200 different types of cells that make up a human. Each of these germ layers is positioned in a manner consistent with the body plan of a human. The ectoderm which gives rise to the skin is positioned on the outer surface of the embryo. Beneath the ectoderm, the mesoderm is positioned where it will give rise to cells such as those giving rise to muscle and bone. The mesoderm overlays the endoderm, the lineage that will give rise to the digestive system. During this time, the future axes also become established. Thus, after gastrulation, much of the future body plan of the developing human has been mapped out.