Question Detail
Question
In primitive chordates Gastrulation begins as the surface of the blastula invaginates into the: a. Blastocyst b. Blastocoel c. Inner cell mass d. Mesoderm
Correct Answer
Option B is the correct answer.
Detailed Explanation
In primitive chordates like the amphioxus, gastrulation begins with the invagination (inward folding) of the vegetal pole of the blastula. This sheet of cells pushes into the blastocoel, the hollow cavity of the blastula. This process eventually obliterates the blastocoel and creates a new cavity, the archenteron.
Hint
The outer layer pushes *into* the central cavity of the blastula.