Stepwise Protocol of Establishing Embryo Model from A Continuous Totipotent-Like Cell-Based Embryo Model Recapitulates Mouse Embryogenesis from Zygotic Genome Activation to Gastrulation v1

The development of stem-cell-derived models of mammalian embryogenesis has provided invaluable tools for investigating embryo development. However, constructing embryo models that can continuously recapitulate the developmental trajectory, from zygotic genome activation (ZGA) to gastrulation, remains challenging. Here we report the development of a chemical cocktail to induce totipotent-like cells with robust proliferation ability, and leveraged these cells to establish a stepwise protocol to generate a continuous embryo model. This model sequentially mimics mouse embryogenesis from embryonic day 1.5 to 7.5. It recapitulates key developmental milestones, including ZGA in 2-cell embryos, the diversification of embryonic and extraembryonic lineages from 4-cell to 64-cell stages, the formation of blastocysts, and the subsequent developmentinto post-implantation egg cylinders. Notably, these structures undergo gastrulation, as evidenced by formation of a primitive streak-like structure and the subsequent emergence of several early organogenesis hallmarks. Our study opens avenues for modeling mammalian embryogenesis in vitro.