Aim 1. Compare differences in SC abdominal adipogenesis of lean PCOS women vs. age- and BMI-matched controls Subjects and clinical assessment: We will recruit 36 lean (18.5-25 kg/M2) PCOS subjects and 12 age- and BMI-matched controls. Subjects will complete a standardized questionnaire emphasizing menstrual dating, abnormal hair growth and acne. The questionnaire also will annotate age, smoking status, medications, surgical history and family histories of excess hair growth in female relatives and of diabetes in parents or siblings for exclusion criteria and for inclusion of some basic traits as covariates. Subjects also will undergo a physical examination; hirsutism will be scored by the modified Ferriman-Gallwey (mFG) method. Transvaginal sonography (TVUS) will be performed to determine the presence or absence of polycystic ovaries. A screening blood sample will be obtained for determinations of steroid hormones, SHBG, TSH, and prolactin.