Embryonic imprinting perturbations do not originate from superovulation-induced defects in DNA methylation acquisition

Maternal imprint acquisition was not affected by superovulation. Given its aberrant effects during preimplantation development, superovulation must instead disrupt maternal-effect gene products that are required after fertilization for imprint maintenance. These results eliminate imprint acquisition per se as the initial stage of imprint loss and point to the importance of analyses on early embryos after procedures involving oocyte manipulation.