Question

Which one of the following parts serves the function of primary organizer in frog?

• A. Dorsal lip of gastrula
• B. Grey crescent area of frog
• C. Chorda-mesoderm of gastrula
• D. All of the above

Answer 1

The correct option is D All of the above

Grey crescent is a crescent-like and grey colored area developing on the surface of frog egg opposite to the point of sperm entry. It's materials function as the organizer. The grey crescent marks the future dorsal side of the embryo. The first cleavage bisects the grey crescent into two equal halves and this plane represents the future median plane of the embryo. During gastrulation phase of frog, the first cells to form the dorsal lip are endodermal cells. These cells later become the pharyngeal cells of the foregut. The next cells over the dorsal lip of the blastopore are called the chorda mesoderm cells. These cells will form the notochord, a transient mesodermal backbone that is essential for initiating the differentiation of nervous system. Thus, the correct answer is ‘All of the above.’