Improved fertilization and implantation rates after non-touch zona pellucida microdrilling of mouse oocytes with a 1.48 μm diode laser beam

The safety of microdrilling the zona pellucida of mouse oocytes with a 1.48 μm diode laser has been investigated by determining the ability of mouse oocytes to fertilize in vitro and develop in vivo. Mice born after transfer of control and zona pellucida-microdrilled embryos into foster mothers were submitted to anatomical and immunohistochemical investigations, and their aptitude to breed was assessed in two subsequent generations. Decoronization of the oocytes with hyaluronidase induced a reduction of the fertilization and implantation rates, which was attributed to a zona hardening phenomenon. After laser zona pellucida microdrilling, these rates were restored to those obtained with embryos derived from untreated oocyte-cumulus complexes. Pups derived from zona pellucida microdrilled embryos were comparable with those obtained from control embryos, confirming the lack of deleterious effects of the laser treatment. In conclusion, the 1.48 μm diode laser allows safe microdrilling of the zona pellucida of mouse oocytes after decoronization with hyaluronidase. Based on the health of the F 2 generation and the lack of neuroanatomical and neurochemical differences, we concluded that this technology may be investigated in the human, particularly when the zona pellucida represents the main impediment for fertilization or embryo hatching.