Findings on nuclear staining using hoechst dye in cleaved unfertilized eggs obtained by repeated superovulation with gonadotrophin.

Unfertilized eggs showing abnormal cleavage are ovulated with repeated induction of super-ovulation. In this study, the presence or absence of the nucleus was examined in segmented blastomeres of these unfertilized eggs using Hoechst dye. Unfertilized eggs showing a morula stage-like cleavage obtained by repeated superovulation 4 times using PMSG/hCG were collected from mice oviducts. The collected eggs were nuclear-stained using Hoechst dye and examined by fluorescence microscope. No positive staining of the nucleus was observed in any of the blastomeres, and only diffuse fluorescence was noted in the cytoplasm. Therefore, we concluded that no nucleus was present in these blastomeres and that cleavage was a degenerative change.