Viability of Vitrified Biopsied Bovine Embryos after In-straw Dilution

抄録

The objective of the present study was to evaluate the viability of vitrified biopsied bovine embryos. Bovine embryos ranging from the compacted morula to blastocyst stage on day 7 (day 0=day of estrus) were collected from donor females, biopsied for sexing, and vitrified with ethylene glycol (EG) 25% (v/v), dimethylsulfoxide (DMSO) 25% (v/v) and 0.3% (w/v) bovine serum albumin dissolved in PBS using 0.25-ml straws. We assessed the concentrations of cryoprotectants in the straw after in-straw dilution, and the percentages (v/v) were 6.9-7.7% for EG and 2.8-3.3% for DMSO. The pregnancy rate of vitrified-warmed embryos in the in-straw dilution group (ISD group) was 57.9% when embryos were expelled from the straws after diluting the cryoprotectant in the straws, and that the survival of vitrified-warmed embryos were observed before transfer. In contrast, the pregnancy rate in the directly transfer group (DIR group) was 62.5% when embryos were transferred directly to recipients without expelling embryos from the straws. There were no differences among the pregnancy rates of the ISD group, the DIR group and the non-vitrified biopsied embryos (NV group) (56.3%). These results suggest that it was possible to warm the vitrified-biopsied bovine embryos on farms and to transfer them immediately to recipients, yielding a practical pregnancy rate.