Comparison of various cryopreservation media for vitrification of 7-day bovine embryos]

A vitrification medium, attested for cryopreservation of mouse eight-blastomere embryos (6.85 mol/l glycerol as a cryoprotective agent), was checked up with respect to preservation of bovine seven-day morulas and blastocysts. As this medium was not found to be convenient either as to its technical parameters or the reached embryo survival, its composition was modified. The glycerol content was complemented or partly replaced by other cryoprotectives (methanol, saccharose, L-proline). A comparison of technical parameters and viability of rewarmed embryos shows that our requirements (technically simple technique of freezing and rewarming and good survival) are met in the best way by a cryoprotective combination of 4.11 mol/l glycerol and 1.0 mol/l saccharose. The total of 54.5% embryos developed in-vitro conditions following vitrification in the medium of this composition and after rewarming.