The YAG laser used in micromanipulation to transect the zona pellucida of hamster oocytes

Problem Since there has been no reported use of the YAG laser to micromanipulate oocytes, our purpose was to study whether (1) a YAG laser could be used to open the zona pellucida of hamster oocytes; (2) human sperm could reach the ooplasm and (3) under sperm penetration assay conditions, sperm would bind and penetrate the ooplasm.Results A YAG 100 laser was used at 10 W and 0.4-sec pulse width to open eight of eight ooplasm oocytes. The opening in the zonae was 0.25 to 1.0 rad (10 to 40 µm). For the initial eight oocytes and two parallel controls, the coarse appearance of the ooplasm was unchanged after 3 days. Next, in 11 of 12 manipulated oocytes, the sperm clustered at the opening of the zona. When 16 more oocytes were opened and exposed to sperm in sperm penetration assay conditions, each ooplasm bound sperm. There was no penetration noted. Each manipulation time was <1 min. To clarify the laser effect, oocytes were exposed to laser energy then utilized as the interactive surface in the sperm penetration assay. It was found that only 20% bound sperm with no penetration.Conclusion While the time factor compares favorably with other methods of zona opening, further study needs to be performed to minimize effect to the exposed oocyte.