Effect of dilution procedures on the survival of IVF bovine embryos frozen by 1.5M ethylene glycol

概要

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The present study was designed to investigate the effect of temperatures and duration during removal of ethylene glycol as a cryoprotectant after thawing on the survival of frozen bovine IVF embryos. Bovine blastcysts (7 to 8 days after IVF) were frozen in 1.5M ethylene glycol, and then thawed and diluted by the different dilution procedures as follows. A group: Embryos were expelled from straw within 5 min after thawing and placed directly into Dulbecco' s modified PBS supplemented with 20% calf serum (CS-PBS) at room temperature (22-23°C). B group: Embryos were expelled within 5min and placed directly into warm CS-PBS at 37°C. C group: Embryos were kept in the straw for 40min after thawing and placed into warm CS-PBS for dilution. After washing twice, embryos were co-cultured with granulosa cells in TCM-199 supplemented with 5 % calf serum for 48hrs. Blastcystes developed to the hatching stage were estimated as viable ones. Survival rate in B group was slightly higher than A group, although the difference was not significant. Survival rate in C group was significantly lower than B group. These date suggest that embryos frozen with 1.5M ethylene glycol should be diluted in the warm CS-PBS to obtain better survival rate and the duration in straw after thawing might affect the survival and pregnancy rate in direct transfer.
日本哺乳動物卵子学会の論文