Study Of Autologous Implantation Of Cryopreserved Ovarian Tissues In Female Rabbits

OBJECTIVE To assess the histologic and physiological function of the cryopreserved ovarian tissues after autologous implantation in mesometrium ,ovarian bursa and ovary in rabbits.METHODS Fifteen New Zealand White female rabbits with normal estrous cycle were divided into three groups at random, with 5 rabbits in each group.Group 1,fresh ovarian tissues were implanted into mesometrium and ovarian bursa. After oophorectomy, the rabbits were submitted to surgery for the ovarian tissues "sowing" implantation in mesometrium and ovarian bursa, and the ectomy of the implanted tissues and small pieces of endometria 20 days later. Group 2, cryopreserved ovarian tissues were implanted into mesometrium and ovarian bursa. After oophorectomy and cryopreservation for 14 days, the rabbits were submitted to surgery for the thawing ovarian tissues " sowing " implantation in mesometrium and ovarian bursa ,and the ectomy of small pieces of endometria. 20 days later, the second surgery was submitted to ectomize the implanted tissues and small pieces of endometria. Group 3 , cryopreserved ovarian tissues were implanted into ovary. After right oophorectomy and cryopreservation for 14 days, the thawing ovarian tissues was marked by fluorochrome then "sowing"implanted under the cortex of left ovary. The left ovary was ectmized 20 days later. The ovarian and endometrial histology, the survival and development of follicles were detected through light microscope and electron microscope and counting the follicles of every stages. Vaginal cytology was used to assess the secretary function of implanted ovarian tissues. At the same time, the cryopreserved ovarian histology compared with fresh ovary's was used to confirm the effect of cryopreservation.RESULTS No significant differences were observed in the proportions of normal and morphologically changed follicles between frozen-thawed tissues and fresh ovarian tissues ( P > 0.05 ) ,between cryopreserved tissues and implanted cryopreserved tissues ( frozen-thawed group compared with group 2 or group 3, P> 0.05) ,and among implantation groups (group 1,2,and 3 , P>0.05,Table 1) .The percentages of normal follicle in group 1,group 2 and group 3 were lower than that of the fresh ovarian tissues ( P<0.05) . No significant differences were observed in the proportions of every stage follicles between group 2 and group 3. The implanted ovarian tissues in group 1,2,3 all resumed follicle development and no significant differences were observed in the proportions of maturescent follicles between the fresh ovarian tissues and three implanted groups ( P> 0.05).The maturescent follicles in tissues of group 2 and 3 were more than those in frozen-thawed tissues (P< 0.05) .After cryopreservation and implantation, there was no evident changes in ovarian histology and ultrastructure.CONCLUSIONS Cryopreservation of small pieces of ovarian tissue is feasible; After autologous implantation, the cryopreserved ovarian tissues have no significant morphological and ultrastructural changes , the follicles survive and develop well; The effects of different sites for cryopreserved ovarian tissues are similar. Mesometrium, ovarian bursa and ovary are all favourable implantation sites.