A Resource for the Transcriptional Signature of Bona Fide Trophoblast Stem Cells and Analysis of Their Embryonic Persistence

Figure 1

EOMES colocalizes with TSC markers CDX2 and ELF5 in the E7.5 chorionic hinge and expression is lost around E9.5. Immunofluorescence staining shows nuclear EOMES and reporter expression in (a–a′′) the visceral endoderm (VE), the primitive streak (PS), and the extraembryonic ectoderm (ExE) at E6.5, (b) within the chorion (Ch) and the chorionic hinge at E7.5, and (d–d′′) in the chorion at E8.5. Asterisks in (a′) indicates unspecific signals in extraembryonic tissues. (b and b′) TSC markers EOMES and CDX2 colocalize in cells of the chorion at E7.5. EOMES staining is most prominent in the chorionic hinge and shows a gradient along the chorion, while CDX2 does not show graded reduction along the chorion. (c) ELF5 similarly localizes to the chorion with strongest staining in the chorionic hinge and additionally expands into the ectoplacental cone (EPC) adjacent to the ectoplacental cavity (EPCav). (e, e′) Faint EOMES staining can be detected at E9.5 in the region emanating from the chorionic hinge, and (f, f′) staining is entirely lost at E10.5. (e) EOMES can be additionally found in parietal trophoblast giant cells (pTGC) and natural killer cells (NK) at E9.5. Al, allantois; EPC, ectoplacental cone; EPCav, ectoplacental cavity ExE, extraembryonic ectoderm; Ch, chorion; ChH, chorionic hinge; Pl, placenta; PS, primitive streak; pTGC, parietal trophoblast giant cells VE, visceral endoderm; NK, NK cells.