BCL2 and polycystic ovary syndrome: The comparison showed that the Bcl2 expression in the control group significantly increased in the melatonin-free media and at different concentrations of melatonin as compared to the PCOS oocytes, except that the Bcl2 expression in PCOS oocytes was significantly higher at a concentration of 10− 5 M (p ≤ 0.05) as shown in the Fig. 2e.