Objective: To investigate the sex chromosomes and the expression of insulin-like growth factor-II (IGF-II) on activated human unfertilized oocytes after intracytoplasmic sperm injection(ICSI) with calcium ionophore A23187 and puromycin.
Methods: All 95 discarded oocyes that showed no evidence of fertilization at 16-18 h after in vitro maturation and intracytoplasmic sperm injection cycles (IVM-ICSI)/conventional ICSI were exposed to calcium ionophore A23187 (5 micromol/L) for 5 min and then were incubated with puromycin (10 microg/mL) for 4 h. After activation, the oocytes were cultured in vitro for 3-5 days. The sex chromosome analysis was performed by dual color fluorescence in situ hybridization. The expression of IGF-II on the activated embryos, normal embryos, and parthenotes was examined.
Results: The combination of calcium ionophore A23187 with puromycin could activate the unfertilized oocytes 22 h after ICSI. The activated rate, cleavage rate, and quality of activated embryos of the IVM-ICSI group were similar to those of ICSI group, respectively. Sex chromosome analysis indicated that 8 male and 5 female embryos had been derived from two pronucleus and a second polar body. The expression of IGF-II on activated embryos and normal embryos was high and similar, which was much stronger than that of parthenotes.
Conclusion: The combination of calcium ionophore A23187 with puromycin could effectively activate unfertilized oocytes 22 h after ICSI. Moreover, the unfertilized oocytes activated by calcium ionophore A23187 and puromycin had normal sex chromosomes and expression of IGF-II like the normal embryos. These suggest that oocyte activation may be considered as a remedial measure in the presence of total or nearly total fertilization failure in ICSI.