Cryopreservation is an effective method for the long-term storage of fish sperm. However, because of a lack of methods for cryopreserving fish eggs and embryos, a technical challenge remains in preserving maternally inherited cytoplasmic compartments. Here, we aimed to generate functional eggs and sperm in sterile rainbow trout hatchlings by transplanting cryopreserved ovarian germ cells into the peritoneal cavity. Immature ovaries were isolated from 9-month-old transgenic rainbow trout, whose ovarian germ cells expressed green fluorescent protein (GFP), and cryopreservation was optimized by testing several different cryoprotective agents. Dominant orange-colored, pvasa-Gfp transgenic rainbow trout females served as donors, and wild-type triploid rainbow trout served as germ cell recipients. Viability and transplantation efficiencies of frozen ovarian germ cells were stable for up to 1,185 days. Ovarian germ cells frozen for 8months efficiently differentiated into eggs and sperm in the ovaries and testes of recipient fish. Inseminating the resultant eggs and sperm generated viable offspring displaying the donor phenotypes (orange body color, green fluorescence, XX ovaries, and matching karyotype). This study represents the first success in generating functional gametes from cryopreserved female germ cells in any fish species, which should facilitate the conservation of protogynous fishes, female heterogametic fish, and currently endangered fish.

Polyethyleneglycol-adsorbed–superoxide dismutase (PEG-SOD), has been proposed as an effective agent for reducing free radical-mediated injury. The objective of this study was to investigate a protective effect of PEG-SOD supplementation on ovarian tissue during transplantation. Ovaries from F-1 mice were collected and vitrified. After warming, ovaries were autotransplanted under kidney capsule. Mice were randomly divided into four groups according to dose of PEG-SOD, (0 U/ml, 100 U/ml, 1,000 U/ml and 10,000 U/ml respectively). Grafted ovaries were retrieved 2, 7 and 21 days later. PEG-SOD was treated by intraperitoneal injection once every 48 hours and especially for 21 days group, after first week treatment, PEG-SOD was treated once every 4 days. Morphology of ovaries was assessed histological analysis and ELISA for FSH was performed to evaluate restoration of ovarian function. In 2 days groups, morphologically intact follicle ratio of 10,000 U/ml group was significantly higher than other groups. In 7 days groups, morphologically intact follicle ratio was significantly higher in all treatment groups. In 21 days groups, there was no significant difference of intact follicle ratio in total follicles in all groups but intact primordial, primary and secondary follicles ratio was higher in 10,000 U/ml group. FSH levels in blood serum were decrease as time goes on, but there is no statistical difference in each groups. In conclusion, the data of the present study show that PEG-SOD has a beneficial effect on preservation of the morphologically intact follicle.

Objective : To investigate the effects of Simvastatin and Methylprednisolone on ovarian tissue cryopreservation and transplantation using mouse models. Methods : The mice were randomly distributed into 1 control and 3 experimental groups. The B6D2F1 mice were given oral Simvastatin (5 mg/kg), intravenous Methylprednisolone (15 mg/kg), or a combination of both at 2 hours before ovariectomy. Same volume of normal saline was given perorally in the control group at 2 hours before ovariectomy. The ovarian tissues were vitrified accrording to our protocols. The vitrified ovaries were warmed 1 week later and auto-transplanted under bilateral kidney capsules. The ovaries and blood sera were collected at 2, 7 or 21 days after transplantation. Histological analysis, TUNEL assay, immuno-histochemistry for CD31, serum AMH level and embryonic development after in vitro fertilization were assessed for evaluation. Results : With regard to the total grade 1 follicle rate, both Simvastatin or Methylprednisolone treated groups were significantly increased at 2, 7 or 21 days after transplantation (except Simvastatin treated group at 7 days). A combination of Simvastatin and Methylprednisolone group was significantly improved in terms of the total G1 follicle rate, apoptotic follicle rate, CD31 positive area and serum AMH after ovarian tissue transplantation. However, there were no statistically difference with respect to the oocyte maturation rate, blastulation rate, and the other embryonic development parameters after in vitro fertilization procedure among the four groups. Conclusion : Our results suggest that combined donor Simvastatin and Methylprednisolone have beneficial effects on the quality and function of transplanted ovarian tissues.