Scd1 −/− blastocyst give rise to inner cell mess (ICM) impairment and embryo development arrest. (A): Immunofluorescence staining of Cdx2 (Trophectoderm cell marker) in WT and Scd1 −/− Scd1 −/− blastocyst give rise to inner cell mess (ICM) impairment and embryo development arrest. (A): Immunofluorescence staining of Cdx2 (Trophectoderm cell marker) in WT and Scd1 −/− blastocysts. Scale bars, 50 µm. (B): The total cell number of WT and Scd1 −/− blastocysts. Twotailed Student's t-test was used for statistical analysis. The Scd1 −/− group has significantly fewer cell numbers than the WT group (p = 0.0066). Each dot represents one embryo, and black bars indicate the mean cell number for each group. (C): Number of Cdx2 + cells in Scd1 −/− blastocysts compared with WT in 16-32 cells, 32-64 cells and >64 cells embryos, respectively. * p < 0.05 (t-test). (D): Immunofluorescence staining of Sox2 (inner cell mass marker) and Cdx2 in WT and Scd1 −/− blastocysts. Rescue group represent the overexpression of Scd1 in Scd1 −/− blastocysts to reflect the rescue function of Scd1 in ICM generation. Scale bars, 50 µm. (E): Numbers of Sox2 + cells in WT and Scd1 −/− blastocysts. * p < 0.05 (t-test). (F): Morphology of the embryo stem (es) cells isolated from the ICM of WT and Scd1 −/− blastocysts. Bar, 25 µm. (G): The uterus of WT and Scd1 −/− mice when E12.5 of pregnancy. The red arrow marked the embryos' location. Bar, 5 mm. (H): The embryos (E12.5) of WT and Scd1 −/− mice. Bar, 1 mm. (I): The litter size of mice in two groups. ** p < 0.01 (t-test).