CYP24A1 and polycystic ovary syndrome: Therefore, the present study has been undertaken to examine the local VD3 metabolism and the expression of VD3-related molecules (VDR, CYP27B1 and CYP24A1) in ovarian tissue and POAT of control rats (at proestrus and diestrus) and those with PCOS induced by the aromatase inhibitor letrozole.