Background: Polycystic ovary syndrome (PCOS) is the most common cause of infertility, hormonal and metabolic disor-der, 5%–10% of women in reproductive age. some evidence has shown that this disorders cause the disturbance in steroido-genesis pathway. Inofolic is a combination of myo-inositol and folic acid, which improves pathological conditions associated with PCOS and improves fertility. Recently many authors have investigated whether supplementation with inofolic, improved the oocytes’ quality and increase the number of oocytes col-lected after ovarian stimulation in patients with PCOS undergo-ing in vitro fertilization. But so far, no study has examined the signaling pathway of inofolic on steroidogenesis and follicu-logenesis. The aim of this study was to evaluate the effects of inofolic on oocyte quality, fertilization rate, embryo quality and steroidogenesis signaling pathway in cumulus cells of PCOS women undergoing ART cyclesMaterials and Methods: We studied 60 women undergoing IVF using intracytoplasmic sperm injection (ICSI), 40 of them were PCOS And 20 women were non-pco. After randomiza-tion, 20 women received 4 g myo-inositol combined with 400 mg folic acid. and 20 women received 400 mg folic acid alone as placebo. 20 women was non-pcos (control group). The treat-ment was made for 12 weeks, before starting the antagonist cy-cle until the day of ovum pick up. Oocytes and embryos quality were assessed according to (ESHRE) guidelines. The gene ex-pression FSHR, CYP11A1, CYP19A1, ER, StAR, 3β-HSD2 in cumulus cells were analyzed using real-time RT-PCR.Results: The percentage of metaphase II oocyte, fertilization rate and embryo quality significantly improved in the study group which received inofolic (P < 0.05). Furthermore, the gene expression of FSHR, CYP11A1, CYP19A1, ER, StAR, 3β-HSD2 were significantly higher in the study group (P < 0.05) and the gene expression of LHR was significantly lower in the study group.Conclusion: The findings of our study provides some new mo-lecular evidence about the possible mechanism of
Myo-Inositol effect on the fertilization rate, quality of oocytes and embryos in PCOS women undergoing ART cycles. This might be related to modification of steroidogenesis pathway in cumulus cells.