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SlideshowReport

Embryonic Period

Description
About 8 days after implantation, the trophoblast develops into the syncytiotrophoblast and cytotrophoblast.
At around 8 days, the embryoblast also develops into two layers: the hypoblast (primitive endoderm) and epiblast (primitive ectoderm).
Cells of these structures form a flat disc called the bilaminar embryonic disc.
The amniotic cavity forms from the epiblast.
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