In vitro cytotoxic effects of 5-Fluorouracil on isolated murine ovarian preantral follicles

5 fluorouracil (5FU), an antineoplastic drug, is often utilized in the therapeutic regimen for several types of cancer, including the hepatoblastoma in children. The effects of 5FU on the population of ovarian preantral follicles, which is the largest oocyte reservoir, is still poorly understood. The integrity of the ovarian preantral follicle pool is important for lifelong fertility. The better understanding of such effects may favor intervention strategies to protect fertility in 5FU-treated children and women coping with cancer. To analyze the effects of 5FU on isolated murine secondary follicles in vitro, ovaries were collected from young mice (28–30 days old), and secondary follicles were isolated and cultured for 12 days in basic culture medium, with or without 5FU at concentrations of 0.3 mM, 1 mM, 3 mM, 10 mM, and 30 mM. In the in vitro study, we analyzed the percentage of morphologically normal follicles, antrum formation, follicular diameter, and hormone production. On day 12, oocytes were recovered for in vitro maturation. 5FU treatment did not alter the percentage of morphologically normal follicles. On day 12, only 1, 10, and 30 mM 5FU significantly reduced the percentage of antrum. From day 4 onwards, 5FU treatments significantly reduced follicle diameter. The meiosis resumption rate was significantly lower in all 5FU treatments. 5FU concentrations ≥3 mM reduced estradiol levels. In conclusion, 5FU does not affect follicular morphology. However, 5FU deleteriously affects follicular growth, estradiol production, and oocyte maturation in isolated ovarian follicles. •5-FU treatment did not alter the percentage of morphologically normal follicles.•From day 4 onwards, 5-FU treatments significantly reduced follicle diameter.•The meiosis resumption rate was significantly lower in all 5-FU treatments.•5-FU concentrations ≥3 mM reduced estradiol levels.