A developmental coordinate of pluripotency among mice, monkeys and humans.

The epiblast (EPI) is the origin of all somatic and germ cells in mammals, and of pluripotent stem cells in vitro. To explore the ontogeny of human and primate pluripotency, here we perform comprehensive single-cell RNA sequencing for pre- and post-implantation EPI development in cynomolgus monkeys (Macaca fascicularis). We show that after specification in the blastocysts, EPI from cynomolgus monkeys (cyEPI) undergoes major transcriptome changes on implantation. Thereafter, while generating gastrulating cells, cyEPI stably maintains its transcriptome over a week, retains a unique set of pluripotency genes and acquires properties for 'neuron differentiation'. Human and monkey pluripotent stem cells show the highest similarity to post-implantation late cyEPI, which, despite co-existing with gastrulating cells, bears characteristics of pre-gastrulating mouse EPI and epiblast-like cells in vitro. These findings not only reveal the divergence and coherence of EPI development, but also identify a developmental coordinate of the spectrum of pluripotency among key species, providing a basis for better regulation of human pluripotency in vitro.