[Effects of Vitrification with Self-made Carriers and Slow Programmed Freezing on Ovarian Tissue of Sheep]

Objective To investigate the effects of self-made carriers on the cryopreservation of ovarian tissue of sheep. Methods Thirty-two ovaries were randomly assigned to fresh group,programmed freezing group,self-made carrier I vitrification group,and self-made carrier Ⅱ vitrification group.The morphology,proliferation,apoptosis,and estrogen level of the ovarian tissue in each group were observed. Results After cryopreservation,the morphology normal rate of the primordial follicles in programmed freezing group,self-made carrier I vitrification group,and self-made carrier Ⅱ vitrification group were 74.2%,72.8%,and 72.3%,respectively,lower than that(83.7%)in the fresh group(χ²=13.079,P=0.004).The percentage of normal primary follicles in programmed freezing group was lower than that in the fresh group(χ²=12.486,P=0.000).The percentage of normal primary follicles showed no significant difference between vitrification groups and fresh group(P=1.000,P=0.972).There was no significant difference in estrogen level or the positive expression rate of PCNA among the 4 groups(F=0.363,P=0.780;χ²=0.359,P=0.949).The number of apoptotic cells in cryopreservation groups was significantly higher than that in the fresh group(F=37.584,P=0.000),and it was significantly higher in the programmed freezing group than in the two vitrification groups(F=18.992,P=0.000). Conclusion Compared with slow programmed freezing,the vitrification with self-made carriers could well preserve the activity of cells in large sheep ovarian tissue blocks.