A Study On The Morphology And Function After Freezing, Thawing, And Autotransplantation Of Ovarian Tissue In Rats

Objectives: To study the restoration of ovarian steroid secretion and the follicle development after autotransplantation of cryopreserved rat ovarian tissues.Methods: The rat ovarian tissues were suspended in a cryoprotectant solution containing l.Smol dimethylsulfoxide I"1 and slowly frozen in a programmable freezer. Then the tissues were stored in liquid nitrogen for up to 2 weeks and fast thawed. Fresh and frozen-thawed ovarian tissues were autotransplanted heterotopically (in the right inguinal vascular plexus) to the bilaterally ovariectomized adult female rats. Vaginal smears were taken daily after transplantation to observed the restoration of oestrous cycles. On week 4 and 8 after transplantation the grafts were removed and underwent histological examination. Serum estrodiol and progesterone levels were determined.Results: 80.6% of the recipients in fresh group and 48.5% in frozen-thawed group resulted in restoration of regular oestrous cyclic activity; this value was significantly different between the two groups (P<0.01). The vaginal cytology showed trophic maturation within 8.72+1.69 daysor 18.15+2.48 days after transplantation in the fresh and frozen-thawed groups, respectively; statistically significant difference (P<0.01) was demonstrated between the two groups. The mean oestrous days of the fresh group, frozen-thawed group and sham group were 6.25+2.40days, 6.65 +1.90days and 5.09 + 2.14days, respectively; there is no statistically significant difference (P>0.05). The results of serum estrodial and progesterone showed statistically significant difference (P<0.05) on week 4 after transplantation between the frozen-thawed group and fresh group or sham group; no significant difference was observed on week 8 after transplantation. Lots of vasculars, follicles in different developing stages and corpora luteas were observed on week 4 and week 8 after transplantation in both the fresh grafts and frozen-thawed grafts according histological examination.Conclusions: Cryopreserved rat ovarian tissues can be autotransplanted heterotopically with subsequent restoration of hormone secretion and the follicle development. It is a practical and efficiency method to autotransplantation the cryopreserved ovarian tissues heterotopically without vascular anastomosis. This study provides an perspective option for storing female ovarian function.