Ex utero Mouse Embryogenesis from Pre-Gastrulation to Late-Organogenesis

Establishment of the mammalian body plan occurs shortly after the embryo implants into the maternal uterus, and our understanding of post-implantation developmental processes remains limited. While methods for in vitro culture of pre- and peri-implantation mouse embryos are routinely utilized, approaches for robust culture of post-implantation embryos from egg cylinder stages until advanced organogenesis remain to be established. We develop herein highly stable ex utero post-implantation mouse embryo culture platforms, that enable appropriate development of embryos before gastrulation (E5.5) until the hind limb formation stage (E11). Late gastrulating embryos (E7.5) are grown in 3D rotating bottles settings, while extended culture from pre-gastrulation stages (E5.5 or E6.5) requires a combination of novel static and rotating bottle culture protocols. Histological, molecular, and single cell RNA-seq analysis validate that the ex utero developed embryos recapitulate precisely in utero development. This culture system is amenable to introducing a variety of embryonic perturbations and micro-manipulations that can be followed ex utero for up to 6 days. Establishment of a system to robustly grow normal mouse embryos ex utero from pre-gastrulation to advanced organogenesis represents a valuable tool to investigate post-implantation embryogenesis, eliminating the uterine barrier to mechanistically interrogate morphogenesis and tissue specification in mammals. Overall design: Mouse embryos at E6.5 days post fertilization were cultured ex utero 2 days (equivalent to E8.5) and 4 days (equivalent to E10.5) and analyzed by single cell RNA seq. In utero developed embryos at matched stages were sequenced as control RNA-seq was measured in vitro mouse ESCs and EpiSCs