Typical hormonal profiles are accompanied by increased immunoreactivity of theca folliculi steroid 17 alpha-hydroxylase P450 in polycystic ovary syndrome.

The localisation and expression of steroid 17 alpha-hydroxylase had been studied in ovaries obtained from 40 patients in whom polycystic ovary syndrome (PCO) was diagnosed, and in 15 normal ovaries. In patients, elevated serum LH and testosterone and normal FSH, prolactin and dehydroepiandrosterone levels were recorded. Serum oestradiol concentration was slightly decreased. Immunohistochemical staining with the use of antibody directed against human cytochrome P450c17 (CYP17) revealed that in polycystic as well as in normal ovaries, steroid 17 alpha-hydroxylase is localised mainly in the thecal cells of atretic follicles and in the interstitial cells of the stroma. Greater intensity of the immunohistochemical reaction in the polycystic ovaries than in normal controls, indicates a higher concentration of CYP17 and suggests increased expression of steroid 17 alpha-hydroxylase. It is postulated that the increased expression of ovarian steroid 17 alpha-hydroxylase is an important contributory factor in the pathogenesis of PCO.