No abstract

Background and Objective A non‐touch laser‐induced microdrilling procedure is studied on mouse zona pellucida (ZP). Study Design/Materials and Methods A 1.48‐μm diode laser beam is focused in a 8‐μm spot through a 45× objective of an inverted microscope. Mouse zygotes, suspended in a culture medium, are microdrilled by exposing their ZP to a short laser irradiation and allowed to develop in vitro. Results Various sharp‐edged holes can be generated in the ZP with a single laser irradiation. Sizes can be varied by changing irradiation time (3–100 ms) or laser power (22–55 mW). Drilled zygotes present no signs of thermal damage under light and scanning electron microscopy and develop as expected in vitro, except for a distinct eight‐shaped hatching behavior. Conclusion The microdrilling procedure can generate standardized holes in mouse ZP, without any visible side effects. The hole formation can be explained by a local photothermolysis of the protein matrix. © 1996 Wiley‐Liss, Inc.

The safety of microdrilling the zona pellucida of mouse oocytes with a 1.48 microm 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 microm diode laser allows safe microdrilling of the zona pellucida of mouse oocytes after decoronization with hyaluronidase. Based on the health of the F2 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.