Vitamin C Synergistically Enhances Protective Effects of Vitamin E Against Preantral Follicle Degeneration of Ovine Vitrified/Warmed Ovarian Tissue

This study aimed to evaluate whether the addition of vitamins E and C as two conventional antioxidants improves the cryotolerance of preantral follicles enclosed in ovine ovarian tissue slices. For this purpose, ovarian slices were obtained from abattoired juvenile lambs and randomly distributed to the following groups: fresh, toxicity, vitrified (control), and three treatment groups in two experiments. Vitamin E, vitamin C, or vitamin E + C was added to the vitrification media alone in the first experiment and added to all vitrification, warming, and culture media in the second experiment. Finally, the treated tissues were cultured in vitro for 12 hours. The histological analysis showed that single or combined use of vitamins E and C increases intact preantral follicles in comparison to the control in two experiments (p < 0.05), and simultaneous use of vitamins E and C had a synergistic effect on increasing the percentage of normal preantral follicles in experiment 2 (p < 0.05). Due to the better results in Experiment 2, stromal cell density, antioxidant activity, and molecular evaluation were followed only in this experiment. The vitamin E + C group had higher stromal cell density compared with control group (p < 0.05). Vitamin E strengthened antioxidant capacity compared with the control and vitamin C groups (p < 0.05). This effect was exacerbated when used in combination with vitamin C (p < 0.05). The expression of all evaluated genes (BMP4, BMP15, GDF9, and KITLG) was significantly increased in ovarian tissue treated with vitamin E + C compared with the control group (p < 0.05). This increase was also observed in BMP4, GDF9, and KITLG genes compared with the vitamin C group (p < 0.05). In conclusion, this study revealed the positive effects of vitamins E and C on preantral follicle viability and to some extent a synergistic action of vitamin C on the protective effects of vitamin E against preantral follicle degeneration and increasing antioxidant capacity and development of preantral follicles after ovine ovarian tissue vitrification.