Global demethylation in male and female pronuclei during pronucleus stages within individual zygotes. (A) The DNA methylation levels of different genomic regions of metaphase II oocytes and the first polar bodies within the same gametes. (B) Hoechst 33342 staining of pronuclei in the zygotes, indicating the distance between each pair of male and female pronuclei in individual zygotes. From zygote 1 to zygote 5, the distance between the male and female pronuclei gradually decreases. (C) Global methylation levels in male and female pronuclei within the same zygotes. Note that the methylation levels decrease significantly in both male (red line) and female (blue line) pronuclei.
