Planting Ice Temperature And Sucrose Concentration In Mice Of M ¢ò Egg Cryopreservation

Objective:To study the effects of different and sucrose concentrations in the cryoprotectant solution on the oocytes structure and the potential developmental ability of mice frozen-thawed metaphaseⅡstage oocytes. Method:372 oocytes were collected from five to eight-week-old female mice.The selected MⅡstage oocytes were divided randomly into three experimental groups:A,B and C. The oocytes in Group A were frozen with 0.1M sucrose concentrations in the cryoprotectant solution,seeding at -6℃. Group B was frozen with the same cryoprotectant as Group A, seeding at -7℃.In Group C,the cryoprotectant solution contained 0.2M sucrose and the seeding temprature was -7℃.The qualitative evaluation were given to thawed oocytes.Fertilization was applied to high quality oocytes,followed by further zygotes and embryo culture. The oocytes survival, fertilization and development were observed and compared. Result:(1)It was showed that the cleavage rates in Group A(82.35%) were significantly higher than Group B(38.46%) (P<0.05).But there were no significantly difference about the survival rates, fertilization rates and the rate of high quality thawed oocytes and embryos between the Group A and Group B with different seeding temprature.(2) Between the Group B and Group C with different sucrose concentrations in the cryoprotectant solution,the survival rates and cleavage rates in Group C with 0.2M sucrose concentrations was higher than that in Group B with 0.1M sucrose concentrations(82.61% VS 68.24%,P<0.05;76.92% VS 38.46%,P<0.05).There were significantly statistical difference.More than that,there was significantly difference in the rate of high quality thawed oocytes(78.26% VS 52.94%,P<0.01). But there were no significantly difference about the fertilization rates and the rate of high quality embryos. Conclusion:The cleavage rates in Group A were significantly higher than Group B. The survival rates,cleavage rates the rate of high quality thawed oocytes in Group C were significantly higher than that in Group B.The results provide the clue that rising seeding temprature can facilitate oocytes cryopreservation and benefit the cleavage.Increasing the sucrose concentration to 0.2M in the cryoprotectant solution improve MⅡoocytes cryopreservation.