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What happens to the blastocoel during gastrulation?
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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.
During gastrulation, the blastocoel undergoes significant changes as the embryo rearranges its cells to form the three germinal layers. As the archenteron—the primitive gut cavity—forms and expands, the blastocoel is typically reduced or obliterated.12
The extent of this reduction varies by species:
- Obliteration: In many animals, such as the amphioxus and amphibians, the inward movement of cells causes the blastocoel to be almost completely squeezed out or reduced to a narrow crevice between the ectoderm and the inner layers.2
- Persistence: In echinoderms, a smaller portion of the blastoderm invaginates, allowing the blastocoel to remain as a spacious internal cavity. In these organisms, it persists as the primary body cavity.2
Ultimately, the transformation of the blastula involves shifting cell material so that the ectoderm, mesoderm, and endoderm reach their correct spatial positions for further development.12