LASER-ABLATION OF THE MOUSE ZONA-PELLUCIDA FOR BLASTOMERE BIOPSY

Purpose: A xenon-chloride non-contact laser system was evaluated for o pening the mouse zona pellucida prior to embryo biopsy. Methods: A 308 nm beam was directed into the rear inlet of an inverted microscope, a nd exited to the target through a 100x quartz objective, Following las er opening of the zona, blastomere removal was performed. Results: Eig ht-cell mouse embryos (n = 611) were isolated for this study. Ninety-o ne percent of laser biopsy embryos proceeded to the blastocyst stage c ompared to 94% for acidified Tyrode's biopsied embryos and 83% for zon a-intact controls, Many of the laser exposed embryos, however, exhibit ed morphologic aberrations such as isolated blastomere arrest and embr yo growth delay, Thirty-four percent of the laser biopsy embryos impla nted compared with 47% and 37% for acid biopsied and control embryos, respectively. A significant decrease in fetal development following la ser zona opening, however, was noted. Conclusions: Though this laser s ystem does allow for blastocyst formation and implantation following b iopsy, the possible detrimental effects on embryonic and fetal develop ment should be further evaluated.