Gastrula |
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| Archenterons; Blastopores; Gastrocoeles; Gastrulas; Gut, Primitive; Guts, Primitive; Primitive Guts; Primitive Streaks; Streak, Primitive; Streaks, Primitive | |
| The embryo in the early stage following the blastula, characterized by morphogenetic cell movements, cell differentiation, and the formation of the three germ layers. | |