Viability of Vitrified Biopsied Bovine Embryos after In-straw Dilution

Abstract: 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 emb...