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Multiple Choice
During gastrulation in frogs, a rod of mesoderm under the dorsal surface forms the _____.
A
somite
B
neural tube
C
blastocoel
D
notochord
Verified step by step guidance
1
Understand the process of gastrulation: Gastrulation is a critical phase in embryonic development where the three germ layers (ectoderm, mesoderm, and endoderm) are formed. In frogs, this process involves the movement and differentiation of cells to establish the body plan.
Focus on the mesoderm: The mesoderm is the middle germ layer that gives rise to various structures, including muscles, bones, the circulatory system, and the notochord. During gastrulation, specific regions of the mesoderm are patterned to form these structures.
Identify the dorsal mesoderm: In frogs, the dorsal mesoderm is located under the dorsal surface of the embryo. This region is crucial for forming the notochord, a rod-like structure that provides support and signals to the overlying ectoderm to form the neural tube.
Understand the role of the notochord: The notochord is a defining feature of chordates. It serves as a scaffold for the developing embryo and plays a key role in inducing the formation of the neural tube, which will later develop into the central nervous system.
Eliminate incorrect options: The somite forms later from the paraxial mesoderm and contributes to muscles and vertebrae. The neural tube arises from the ectoderm, not the mesoderm. The blastocoel is a fluid-filled cavity present earlier in development, not a structure formed during gastrulation. Therefore, the correct answer is the notochord.