Ma, H. et al. Science 366, eaax7890 (2019).

Niu, Y. et al. Science 366, eaaw5754 (2019).

The early post-implantation stage is critical in the development of a mammalian embryo. During this time, the association with maternal tissue is set up and strengthened, and the embryo itself undergoes formative rearrangements as the anterior–posterior axis emerges and the germ layers are formed. Mouse embryogenesis differs from human embryogenesis during this time, and more suitable models are therefore desirable. Ma et al. and Niu et al. have established culture conditions for macaque embryos that allow development up to 20 days post-fertilization. Embryos cultured under these conditions undergo the major developmental processes of primate post-implantation processes. They form epiblast and hypoblast lineages, they establish amniotic and yolk sac cavities, they generate primordial germ cells, they specify the anterior–posterior axis, and they gastrulate. This technology provides access to the transcriptomic and epitranscriptomic program at a crucial developmental stage and enables lineage studies in macaque embryos.