Practice question

Trophectoderm identity is driven by transcription factor Cdx2 acting as master regulator opposing pluripotency program. In outer blastomeres Hippo pathway inactive, YAP translocates to nucleus complexing with TEAD4 to activate Cdx2 expression. Cdx2 then drives genes for epithelial polarization, water transport and invasion while directly repressing Oct4 and Nanog transcription. Forced Cdx2 expression converts embryonic stem cells into trophoblast stem cells. Hence Cdx2 promotes differentiation toward placental lineage rather than embryonic lineages, establishing first cell fate decision, implantation competence, extraembryonic commitment essential for pregnancy and placental patterning processes.