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Why does the blastopore not always become an animal's adult mouth?
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Animal development
The embryos of many animals appear similar to one another in the earliest stages of development and progress into their specialized forms in later stages.
In animal development, the blastopore is the opening of the gastrula that connects the primitive gut, or archenteron, to the exterior. While it is sometimes historically referred to as a "primitive mouth," this term is misleading because the blastopore does not always develop into the adult mouth.12
The fate of the blastopore varies significantly across different animal groups:
- Mouth formation: In some animals, the blastopore directly evolves into the adult mouth.1
- Anus formation: In other animal groups, the blastopore becomes the anus, and the mouth forms later as an entirely new opening.12
- Alternative pathways: In certain species, the blastopore may be covered over entirely, eventually contributing to the canal that connects the primitive gut to the cavity of the neural tube.1
Because of these diverse developmental pathways, the blastopore serves as a fundamental structural landmark during gastrulation rather than a fixed precursor to the mouth.2