- Gastrulation: process converting the bilaminar into the trilaminar embryonic disc, forming the three primary germ layers, ectoderm, mesoderm and endoderm.
- All body tissues and organs arise from one or more of these three germ layers.
Formation of the Trilaminar Embryonic Disc
Important: The figure uses older ectoderm/endoderm terminology for the bilaminar layers. Interpret these layers as epiblast and hypoblast; definitive ectoderm and endoderm form during gastrulation.