If PCOS-like monkey theca and/or granulosa cells exhibit insulin resistance in terms of metabolic signaling, such as diminished postprandial insulin-mediated glucose uptake, diminished expression of FSH/LH receptors and relevant steroidogenic enzymes such as CYP11A1, CYP17A1, HSB3B2 and CYP19A1, might occur and impair follicle selection. The gene discussed is CYP19A1; the disease is polycystic ovary syndrome.