The mural TE differentiates into primary P-TGCs as previously reported 28 . The polar TE can give rise to TSCs which are common progenitors of LaTP cells, EPC cells, and secondary P-TGC cells. Secondary P-TGCs are differentiated from TSCs and ExE cells via secondary P-TGC progenitor cells. The S-TGC branch and spongio-branch have the same progenitor cells, and their fates are determined when the EPC structure forms (before chorioallantoic fusion). SpA-TGCs and Gly-T cells are both differentiated from SpT. TFs associated with each developmental process are indicated beside the corresponding arrow. The cell clusters with colored backgrounds (except for the gray background) were newly identified. The number in parentheses next to the cell type represents the cell cluster. The markers of terminally differentiated cell types are listed below the corresponding cell types. TE trophectoderm, TSC trophoblast stem cell, ExE extraembryonic ectoderm, EPC ectoplacental cone, SpT spongiotrophoblast, LaTP labyrinth trophoblast progenitor, P-TGC parietal trophoblast giant cells, Gly-T glycogen trophoblast, SpA-TGC spiral artery-associated trophoblast giant cells, S-TGC sinusoid trophoblast giant cells, S-TGC-P sinusoid trophoblast giant cell precursor, SynT I/II syncytiotrophoblast layer I/syncytiotrophoblast layer II.
