The Use of Laser-assisted Hatching in Bovine in Vitro Produced Embryos to Improve Pregnancy Rate

The Use of Laser-Assisted Hatching in Bovine in Vitro Produced Embryos to Improve Pregnancy Rate. (August 2008) Suzanne Lynn Menges, B.S., Texas A&M University Chair of Advisory Committee: Dr. Duane Kraemer In vitro produced (IVP) embryos not hatching from the zona pellucida (ZP) after transfer is one possible contributing factor of a lower pregnancy rate when compared to in vivo embryos. This study evaluates using a microscope objective mounted laser to cut the ZP prior to transfer into the recipient to assist hatching. The preliminary data evaluated the effect of laser treatment on IVP embryos and subsequent blastomere survival. In six replicates, bovine oocytes were in vitro produced according to the standard laboratory procedures of TransOva Genetics, Sioux Center, IA. On days 5, 6, and 7 of in vitro culture, embryos were randomly divided into 3 groups: no treatment (Control; n=63), sham ZP cut (Sham; n=68), or ZP cut (Cut; n=70). Control embryos were immediately returned to the incubator. Sham embryos were exposed to all conditions as Cut except laser assisted hatching. The XyClone® system was used to treat the Cut group using pulse strength of 90% and pulse length of 600 μsec. Embryos were returned to culture until day 8 when embryonic development and the percentage of live cells were determined and analyzed with Chi square. The number of developing embryos