(a) Schematic (upper) and merged Hoffman and Hoechst 33342 (DNA) fluorescence images showing phICSI-13. Red arrowheads indicate sperm heads. (b) Merged Hoffman and Hoechst 33342 (DNA) images (upper) at the times indicated after sperm injection in phICSI-13. Schematic (centre: paternal genome, black; second polar body, pink) and fluorescence images (BrdU, maternal genome; PI, both genomes) show different classes of nuclear configuration 14 h after the first mitotic division (1C→2C) in phICSI-13. White arrowheads, paternal chromatin. Scale bars, 20 μm. Pie charts show proportions of each nuclear class in phICSI-7 (n=117) and phICSI-13 (n=77). (c) Hoffman (upper) and fluorescence micrographs of embryos generated by injecting mII oocytes (ICSI-1bla) or parthenogenotes (phICSI-13-1bla) with sperm carrying a transgene encoding mCherry expression driven by the Oct4 promoter (pOct4-mCherry). Scale bar, 50 μm. (d) Histogram showing relative intensities of mCherry expression (±s.e.m.) of c in ICSI-1bla (open) and phICSI-13-1bla (red) embryos (n=25 [2C, blast] or 27 [4C, mor, mor/blast]). Experiments were on 2 days. Embryo stages are 4-cell (4C), morula (mor), morula-blastocyst (mor/blast) and blastocyst (blast). Differences are shown where P<0.05 (two-tailed, unpaired t-test).