Question

Which of the following is not correct for gastrulation?

• A. Archenteron is formed
• B. All germinal layers are formed
• C. Morphogenetic movements
• D. Blastomeres and gastrocoel degenerate

Answer 1

The correct option is D Blastomeres and gastrocoel degenerate

The process by which the blastula becomes a three-layered embryo, or gastrula, is called as gastrulation.

Thus, early development proceeds through the following stages:

Zygote-> early cleavage stages -> morula -> blastula -> gastrula.

During gastrulation, the embryo begins to approximate its body plan as cells arrange themselves into three distinct germ layers, or embryonic tissue layers the outermost layer, the ectoderm, the innermost, the endoderm, and the mesoderm, which develops between them. Additional cell divisions take place during gastrulation and the germ layers become established through a combination of processes. Many cells lose their old cell-to-cell contacts and establish new ones through cell recognition and adhesion processes involving interactions among the integrins and other plasma membrane proteins and the extracellular matrix. Many cells undergo cytoskeletal changes, particularly alterations in the distribution of actin microfilaments, these changes in the internal architecture of the cells allow them to change shape and/or undergo specific, directional, amoeboid movements. As a result of these movements, many cells ultimately take up new positions in the interior of the embryo. Each of the germ layers develops into specific parts of the embryo. During gastrulation blastocoel disappears and is replaced by archenteron, the primitive gut. The blastomeres are rearranged.

Therefore, the correct answer is option D.