EFFECTS OF PRE TREATMENT ANO LACTOSE CONCENTRATION ON ULTRA RAPID FREEZING MOUSE MORULAE

Alceu Mezzalira Mara Iolanda Batistella Rubin About the authors

SUMMARY Two hundred and twenty five morulae were submitted to a ultra rapid freezing in four different treatments. In treatment I (n=57), the embryos were first exposed to a 5.0M glycerol pre treatment, and later to a glycerol 5.0M + lactose 0.25M freezing solution. In the treatment II (n=54) the procedure was similar to the treatment I, but with 0.5M of lactose instead 0.25M. In the treatment III (n=57), the embryos were exposed directly to a glycerol 5.0M + lactose 0.25M freezing solution. In the treatment IV (n=57) the procedure was similar to the treatment III, but with lactose 0.5M instead 0.25M. The embryos were maintened 5 minutes in each solution, and then loaded in groups of 6 to 12, in 0.25ml plastic straws. After thawing in a water bath at 37 °C, the cryoprotector was removed by five minutes exposure to a lactose solution in the same concentration than that used in the freezing procedure. After 48 hours of culture, the highest viability was observed in treatment IV (80.7%), followed by treatment III (66.7%), treatment II (66.7%) and treatment I (31.6%). Pretreatment determined a decrease in the viability (49.2%) when compared with the viability of groups without pre treatment (73.7%). The embryo viability was higher with lactose 0.5M (73.7%) than with lactose 0.25M (49.2%).

ultra rapid freezing; pretreatment; lactose


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