DEVELOPMENTAL COMPETENCE OF MOUSE EMBRYOS FOLLOWING ZONA DRILLING USING A NONCONTACT HOLMIUM, YTTRIUM SCANDIAN GALLIUM GARNET (HO-YSGG) LASER SYSTEM

The purpose of this study was to assess the efficacy of the holmium:yt trium scandian gallium garnet (Ho:YSGG) laser, operating in a pipette- free, non-contact mode, to assist hatching and sustain normal embryoni c development. Two-cell mouse embryos were recovered and assigned to l aser-assisted hatching (LAH) treatment or control human tubal fluid (H TF) culture with or without serum (HTF-s, HTF-o) or with late serum su pplementation (HTF-o/s). The basic experimental apparatus for LAH cons isted of a stationary 2.1 mu m Ho:YSGG laser beam directed through a m echanical shutter into an input port of a Zeiss Axiomat inverted micro scope. Fewer (P < 0.05) embryos developed to the blastocyst stage in t he HTF-s group (81%) than in the LAH (90%), HTF-o (94%) and HTF-o/s (9 2%) groups, The level of hatching was significantly increased (P < 0.0 1) after the LAH treatment (57%) compared to HTF-o/s (32%), HTF-s (18% ) or HTF-o (5%), Implantation rates were not significantly impaired fo llowing the LAH treatment (21%). These data demonstrate that LAH using the Ho:YSGG laser is a simple, accurate and effective procedure for a ssisted hatching.