Duplication of the sperm genome by human androgenetic embryo production: towards testing the paternal genome prior to fertilization

There is currently no technique for evaluating the sperm genome before fertilization. However, sperm genome duplication could offer a way forward, whereby one of the sister blastomeres of a 2-cell haploid androgenetic embryo could be analysed. A method was developed for production of human androgenotes by enucleation of oocytes at telophase II (TII) after intracellular sperm injection (ICSI). The results were compared with those obtained via the more usual procedure of oocyte enucleation at metaphase II (MII) prior to ICSI. TII enucleation led to an improvement in the rate of embryo survival, increased the production rate of 1PN-embryos, and also the production of 2- to 8-cell-stage embryos (85.0, 74.9 and 65.8% in TII enucleation, versus 73.8, 48.9 and 33.3% in MII enucleation). Fluorescence in-situ hybridization (FISH) analysis of 30 2- to 5-cell androgenic embryos for two to seven chromosomes revealed the correct chromosome distribution in 76.7% of haploid human androgenotes.