Study on the morphology and function after ultrarapid cryopreservation of ovarian tissue in rats

Objective: To observe the effects of cryopreservation on morphology and function of rats ovarian tissues after ultrarapid freezing.Methods: Cryopreservation of rats ovary pieces was accomplished by direct plunging into liquid nitrogen.Histological sections of fresh and cooled ovarian pieces were analyzed and the number of viable primordial follicles was counted.Fresh and frozen-thawed ovarian pieces were autotransplanted heterotopically(in the back subcutis) to the bilaterally ovariectomized adult female SD rats. After transplantation,the serum levels of E2 were determined.Results: The number of normal primordial follicles in fresh and cryopreserved tissue samples was not significantly different.The results of serum estradiol showed no significant difference(P0.05) after transplantation in 35 days between the frozen-thawed group and the fresh group or the sham group.Conclusion: Cryopreservation by direct plunging pieces into liquid nitrogen is an effective way to preserve rats' ovarian pieces.