Venus Trap in the Mouse Embryo Reveals Distinct Molecular Dynamics Underlying Specification of First Embryonic Lineages

The study explored early mouse embryonic development by using Venus fluorescent protein to track gene expression in embryos, focusing on the specification of the trophectoderm (TE) and inner cell mass (ICM) lineages. Researchers identified 16 founder mice with 65 integrations, with 23 expressing Venus in the blastocyst. They found that Tmem50b was upregulated in outer cells after asymmetric cell divisions, indicating its role in TE lineage specification, while 2610305D13Rik expression in ICM cells became significant later, suggesting different regulatory mechanisms. The study provided a comprehensive lineage map and revealed distinct mechanisms for TE and ICM specification, laying the groundwork for future research on gene networks in early embryonic development.