Autologous heterotopic transplantation of intact rabbit ovary after frozen banking at -196°C

Objective: To determine the efficiency of intact ovary after cryopreservation and transplantation in a rabbit model for limited longevity by revascularization ischemia after implantation of frozen-thawed ovarian tissue. Transplantation of an intact frozen ovary with microvascular anastomos has been shown to be feasible with modern cryobiology and microsurgery. Design: Animal study. Setting: University-based teaching hospital. Animal(s): Twelve 5-month-old mature female New Zealand White rabbits. Intervention(s): After bilateral oophorectomy with one ovary saved as a control in formalin-fixed and hematoxylin and eosin-stained paraffin sections, the contralateral intact ovary was used for autologous heterotopic transplantation after freezing and thawing. Main Outcome Measure(s): Density of primordial follicles 6 months after transplantation was measured. Hormone levels and vaginal cytology were followed throughout the oophorectomy and transplantation period. Result(s): Ten of 12 rabbits had restored ovarian function 1 week after transplantation of their intact cryopreserved ovary. At the 6-month posttransplantation follow-up, mean primordial follicle density was statistically significantly lower in the experimental than in the control ovaries (13.99 ± 3.21 vs. 18.68 ± 3.86 per high-power field). The remaining two rabbits, which had cracked mesentery fat adjacent to the ovary after thawing, never regained ovarian function. Conclusion(s): With microsurgery, cryopreservation of an intact rabbit ovary followed by autologous transplantation may overcome revascularization-associated ischemia to save primordial follicles and attain reasonable graft longevity.