Dynamic intrauterine crosstalk promotes porcine embryo implantation during early pregnancy

Dynamic crosstalk between the embryo and mother is crucial during implantation.Here,we comprehensively profile the single-cell transcriptome of pig peri-implantation embryos and corresponding maternal endometrium,identifying 4 different lineages in embryos and 13cell types in the endometrium.Cell-specific gene expression characterizes 4 distinct trophectoderm subpopulations,showing development from undifferentiated trophectoderm to polar and mural trophectoderm.Dynamic expression of genes in different types of endometrial cells illustrates their molecular response to embryos during implantation.Then,we developed a novel tool,Extra Cell Talk,generating an overall dynamic map of maternal-foetal crosstalk using uterine luminal proteins as bridges.Through cross-species comparisons,we identified a conserved RBP4/STRA6 pathway in which embryonic-derived RBP4 could target the STRA6 receptor on stromal cells to regulate the interaction with other endometrial cells.These results provide insight into the maternal-foetal crosstalk during embryo implantation and represent a valuable resource for further studies to improve embryo implantation.