An embryo at the stage following the blastula,consisting of a hollow,two-layered sac of ectoderm and endoderm surrounding an archenteron that communicates with the exterior through the blastopore.

• 原肠胚一种囊胚之后的胚胎，含有中空、两层的外胚层和内胚层，包围着通过胚孔跟外界交流的原肠。