RESUMO
BACKGROUND: Polycystic ovary syndrome (PCOS) is the most common endocrinopathy causing anovulation in women of childbearing age. It has been well established that estrogen receptor-alpha knockout (ERalphaKO) mice display several pathologic ovarian phenotypes of PCOS. The aims of this study were to determine ovarian pathology in new ERalphaKO mice using a CreloxP approach and intra-ovarian ERalpha function as regulating key aspects of PCOS. METHODS: ERalphaKO mice, which were deficient in exon 3 of the ERalpha gene, were used. Immunohistochemical studies were done on ovaries of control and ERalphaKO mice using antibodies specific to ERalpha, ERbeta, inhibin-alpha, and alpha-smooth muscle actin (SMA), as well as histochemical staining using Sudan black-B. RESULTS: All ovaries of ERalphaKO mice were larger than control mouse ovaries and displayed a disrupted theca-interstitial tissue organization, multiple atretic follicles and multiple hemorrhagic cysts. None of the ERalphaKO mouse ovaries showed a corpus luteum. In addition, heavy deposition of Sudan black-B positive foamy cells was seen. The theca externa of preantral immature follicles and hemorrhagic cysts showed strong expression of alpha-SMA. CONCLUSIONS: ERalphaKO mice show hemorrhagic polycystic ovaries and hyperplasia of the theca externa. This study demonstrates that the ERalpha is the functional key to the pathogenesis of PCOS.