Objective To evaluate the impact of slow-freezing process on human ovarian tissue with the standard cryopreservation-thawing protocol of Fertility Protection Center of Beijing Obstetrics and Gynecology Hospital,Capital Medical University.Methods Ovarian tissues of 12 patients were divided into fresh ovarian tissue group(fresh group)and freezing-thawing ovarian tissue group(F-T group).The freezing-thawing protocol was the standard protocol in our center.The number and activity of follicle were examined with Hematoxylin-eosin(HE)staining and calcein-AM(calcein acetoxymethylester)staining,and the proliferation and apoptosis was evaluated with the immunohistochemical staining of Ki-67 and caspase-3.The expressions of apoptosis-related proteins such as caspase-3,bax and FasL between the two groups were compared with Western blotting.Results There were no statistically significant differences in follicle counting and follicle activity in ovarian tissues pre-and post-freezing-thawing(P>0.05),and the positive rate of Ki-67 in ovarian tissues after freezing-thawing was significantly lower than that in fresh ovarian tissues(P<0.05),and there was no statistically significant difference in the positive rate of caspase-3 between the two groups(P>0.05).The expression of caspase-3 protein in ovarian tissues after freezing-thawing was significantly higher than that in fresh ovarian tissues(P<0.05),while the expressions of other apoptosis-related proteins such as bax and FasL were not significantly different(P>0.05).Conclusion The standard cryopreservation-thawing regimen in our center can effectively maintain the follicle number,morphology,and activity in ovarian tissues.After freezing and thawing,the cell proliferation level is decreased.The expression of apoptosis-related proteins such as bax and FasL are not increased,and the expression of caspase-3 is relatively increased.These results suggest our freezing-thawing regimen is good for human ovarian tissue.