Fig. 5. Cts8 overexpression promotes giant cell differentiation. (A) Northern blot hybridization with Cts8 on wild-type and tg^Cts8 placentas showing approximately equal amounts of endogenous (endo. Cts8) and transgenic (tg Cts8) Cts8 mRNA. The transgenic product is a bicistronic Cts8-GFP RNA. (B) Marker expression analysis of E9.5 placentas after ubiquitous transgene activation (Sox2-Cre.tg^Cts8). Note the particularly strong transgene expression in extra-embryonic mesoderm and parietal endoderm. No striking phenotype is observed at this stage. (C) Prl3b1 expression on E16.5 placentas after trophoblast-specific Cts8-activation by mating to Tpbp-Cre mice. The giant cell/spongiotrophoblast layer is enlarged. (D) Trophoblast tissue dissected from E9.5 control and ubiquitously induced Sox2-Cre.tg^Cts8 placentas after 2 days culture stained with DAPI. Fewer diploid but more and bigger giant cells are observed. (E) Quantification of nuclear sizes. No giant cell larger than 1200 µm² was found in controls. Scale bars: 500 µm in B; 1 mm in C; 1 mm in D.