ASSISTED HATCHING IN MOUSE EMBRYOS USING A NONCONTACT HO-YSGG LASER SYSTEM

Purpose: A noncontact holmium:yttrium scandium gallium garnet (He: YSG G) laser system has been designed and tested for the micromanipulation of mammalian embryos. The purpose of this preliminary investigation w as to determine the effectiveness of this laser for assisted hatching and evaluate its impact on embryo viability. The Ho:YSGG system, utili zing 250-mu sec pulses at a wavelength of 2.1 mu m and 4 Hz, was used to remove a portion of the zona pellucida (ZP) of two- to four-cell FV B mouse embryos. Results: In the first experiment there was no differe nce in blastocyst production or hatching rates following laser or conv entional assisted hatching (LAH or AH, respectively) in contrast to co ntrol embryos cultured in a 5% CO2 humidified air incubator at 37 degr ees C. In the second experiment a blastocyst antihatching culture mode l was employed and LAH-treated embryos were cultured in a serum-free H TF medium (HTF-o). Blastocyst formation was nor influenced by LAH trea tment and hatching was increased (P < 0.01) from 4 to 60% compared to HTF-o control group. Conclusions: These preliminary data demonstrate t he utility and nontoxic properties of the Ho: YSGG laser system for qu ick and precise ZP drilling.