FIG. 2.

Mutation in Zpr1 results in cell death and early embryonic death in mice. (A) Differential interference contrast images of wild-type (WT) and mutant (KO) blastocysts (E3.5) at 0 h and after 96 h of culture in vitro. The inner cell mass (ICM) is surrounded by trophoblast giant (TG) cells. Scale bar, 100 μm. (B) Scanning electron micrographs of WT and mutant embryos (KO) cultured in vitro for 96 h. The ICM is growing on the trophectoderm (TE) formed by trophoblast giant cells in WT embryos. The ICM and TE of mutant embryo (KO) display defective growth (top; magnification, ×200; scale bar, 100 μm). Microvilli (MV), projections at the apical surface of cells from wild-type embryos, are absent in mutant (KO) embryos (bottom; magnification, ×1,000; scale bar, 10 μm). (C) In situ detection of caspase activation, using FITC-VAD-fmk and confocal laser-scanning microscopy. Activated caspase (green) in WT and mutant (KO) embryos was observed. Nuclei were stained with DAPI (blue). The mutant embryo exhibited a large amount of caspase activation. Scale bar, 40 μm. (D) Transmission electron micrographs of trophoblast giant cells (top) and cells from the ICM (bottom). The mutant embryo (KO) shows apoptotic bodies (AB) phagocytosed by the trophoblast giant cells, as well as aggregation of heterochromatin and accumulation at nuclear membrane (bottom). Arrowheads show nucleolar accessory bodies (Cajal bodies). Scale bar, 1.0 μm.