In deuterostomes, which structure forms from the blastopore?

In deuterostomes, which structure forms from the blastopore?

• A. Mouth forms from blastopore
• B. Notochord forms during gastrulation
• C. Digestive tract forms from mesoderm
• D. Anus forms from blastopore

Answer: (D)

In deuterostomes, the blastopore becomes the anus. As gastrulation proceeds, a second opening forms to become the mouth, so the blastopore’s fate is tied to the anus, not the mouth. This distinguishes deuterostomes from protostomes, where the blastopore typically becomes the mouth. So the structure arising from the blastopore in deuterostomes is the anus. The mouth forms later from a separate opening, the notochord arises from mesoderm, and the digestive tract is lined by endoderm—none of which directly come from that initial blastopore in these animals.

In deuterostomes, the blastopore becomes the anus. As gastrulation proceeds, a second opening forms to become the mouth, so the blastopore’s fate is tied to the anus, not the mouth. This distinguishes deuterostomes from protostomes, where the blastopore typically becomes the mouth. So the structure arising from the blastopore in deuterostomes is the anus. The mouth forms later from a separate opening, the notochord arises from mesoderm, and the digestive tract is lined by endoderm—none of which directly come from that initial blastopore in these animals.