In vitro fertilization and cleavage of mouse oocytes recombined with the first polar body

The developmental functions of oocytes of three strains of mice (Kunming, ICR and C57BL/6-Tg(CAG-EGFP)C14-Y01-FM131Osb) recombined with the nuclei of first polar bodies (Pbs I) were explored. Cumulus oocyte complexes (COCs) from the mice were collected after superovulation, then Pbs I were obtained from the COCs by 2% pronase treatment. The survival of Pbs I under different temperatures was identified by morphology and trypan blue staining. Later, the polar body I (Pb 1) nucleus and a little cytoplasm was injected into each oocyte, the nuclei of which had been enucleated by micromanipulation. Oocytes recombined with Pbs I were fertilized, then cultured in vitro in order to observe their further development. The results showed that the vigour of Pbs I was maintained for 12–14 h after superovulation, and was still maintained after 48 h at 4 °C. A total of 13 out of 117 recombined oocytes from Kunming and ICR mice, as well as 3 out of 38 recombined oocytes from C57BL/6-Tg(CAG-EGFP)C14-Y01-FM131Osb mice, developed into two-cell embryos. The experiments confirmed that mouse oocytes recombined with the nuclei of Pbs I could maintain fertilization and development. These results present valuable references for further utilization of genetic resources for farm animals