Effect of laser-assisted three area zona thinning at the 8-cell embryo on the hatching of mouse blastocysts

Introduction: This study was aimed to preliminarily examine the effect of laser-assisted three area zona thinning (LAZT) during the cleavage stage of embryo development and the hatching process in mice based on female age. Materials and Methods: C57BL female mice of two different age groups (6-11 and 28-31 weeks) were superovulated and then mated. The 8-cell stage embryos were treated with LAZT in three areas of zona pellucida (ZP) at 120 degrees intervals. The control group was embryos without LAZT. Results: In old mice, LAZT significantly increased blastocyst formation and hatching compared to the control group (82% vs. 38% in number of expanding blastocyst and 66% vs. 20% in number of hatching blastocyst). Conclusion: These results show that multi-area LAZT results in a significant improvement of blastocyst formation and hatching in mice compared to controls.