Developmental competence of mouse embryos following zona drilling using a non-contact holmium:yttrium scandian gallium garnet (Ho:YSGG) laser system.

The purpose of this study was to assess the efficacy of the holmium:yttrium scandian gallium garnet (Ho:YSGG) laser, operating in a pipette-free, non-contact mode, to assist hatching and sustain normal embryonic development. Two-cell mouse embryos were recovered and assigned to laser-assisted hatching (LAH) treatment or control human tubal fluid (HTF) culture with or without serum (HTF-s, HTF-o) or with late serum supplementation (HTF-o/s). The basic experimental apparatus for LAH consisted of a stationary 2.1 microns Ho:YSGG laser beam directed through a mechanical shutter into an input port of a Zeiss Axiomat inverted microscope. Fewer (P < 0.05) embryos developed to the blastocyst stage in the HTF-s group (81%) than in the LAH (90%), HTF-o (94%) and HTF-o/s (92%) groups. The level of hatching was significantly increased (P < 0.01) after the LAH treatment (57%) compared to HTF-o/s (32%), HTF-s (18%) or HTF-o (5%). Implantation rates were not significantly impaired following the LAH treatment (21%). These data demonstrate that LAH using the Ho:YSGG laser is a simple, accurate and effective procedure for assisted hatching.