Disc-like embryonic stage in which differentiation into three layers (endoderm, mesoderm, and ectoderm) has occurred.
Note: In the human embryo this occurs in the third week, following the onset of
gastrulation.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 815 (https://doi.org/10.1515/pac-2015-1202)