An research on the isolation methods of frozen-thawed human ovarian preantral follicles.

OBJECTIVE To explore the effective isolation method for preantral follicles from human frozen-thawed ovarian tissue. METHODS The ovarian cortical tissue was frozen by direct cover vitrification (DCV). The frozen-thawed ovarian tissue was used for isolation of preantral follicles with collagenase combined with mechanical method and mechanical method alone, respectively. RESULTS 1. There was no statistical difference in the survival rates of follicles in various stages between before and after freezing (P > 0.05). 2. The survival rate of secondary follicles was higher, but the survival rate of primordial follicles was lower in mechanical method alone than in collagenase combined with mechanical method (all P < 0.05). 3. The diameters of follicles were larger and E2 levels were higher in mecha-nical method alone than that in collagenase combined with mechanical method (all P < 0.05). CONCLUSION After the frozen-thawed ovarian tissue was cultured for 6 days, compared with collagenase combined with mechanical method, mechanical method alone can obtain higher survival rate of secondary follicles, greater follicular diameter and higher E2 level, which are conducive to follicular subsequent development.