Song WY, Wang Y, Hou XM, et al. - Via performing a randomized, assessor-blinded study, researchers here examined the expression of aquaporin 7 (AQP7) and aquaporin 9 (AQP9) in the granulosa cells of patients with polycystic ovary syndrome (PCOS) and healthy women. In addition, they investigated their localization in oocytes at the germinal vesicle (GV), metaphase I (MI), MII, embryo, and blastocyst stages and the in vitro response to insulin stimulation. Participants were a total of 40 women (aged 20–38 years) consisting of 29 cases of primary infertility and 11 cases of secondary infertility; of these, 17 had an initial diagnosis of PCOS and three received a PCOS diagnosis after an infertility examination. The granulosa cells of patients with PCOS showed higher expression levels of the AQP7 mRNA and protein than those noted in healthy controls. Human oocytes showed AQP7 protein expression at GV, MI, MII, embryo, and blastocyst stages; it was mainly located in the nucleoplasm. Overall the two groups exhibited different localization and expression of AQP7 and AQP9 suggesting the possibility of their involvement in oocyte maturation and embryonic development through different regulatory pathways. Negative correlation of the expression levels of AQP7 and AQP9 was observed with insulin regulation, indicating that insulin might affect the maturation of PCOS follicles by changing AQP7 and AQP9 expression.