has part has part has_part ectoderm formation endoderm formation mesoderm formation gastrulation biological_process A complex and coordinated series of cellular movements that occurs at the end of cleavage during embryonic development of most animals. The details of gastrulation vary from species to species, but usually result in the formation of the three primary germ layers, ectoderm, mesoderm and endoderm. Reactome:R-HSA-9758941 Wikipedia:Gastrulation GO:0007369 embryonic morphogenesis