gastrulation

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gastrulation In the embryogenesis of a vertebrate, the next stage after the blastula, in which the three germ layers differentiate to form the triploblastic embryo and the basic body plan of the vertebrate is laid down. During this stage there is a complicated movement of cells from various positions in the blastula to form the germ layers in an approximation of their final positions. This process usually occurs at the end of the cleavage period.

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