['In the human ovary, expression of anti-Mullerian hormone (AMH) is detected primarily in granulosa cells of preantral and small antral follicles. This finding is consistent with the tight correlation between circulating AMH levels and the number of small antral follicles (2-5 mm) in normal and polycystic ovary syndrome (PCOS) women. In addition, the greater follicle count in PCOS is mirrored by significantly higher serum AMH levels compared with those of normal women. Despite the utility of AMH measurements in evaluating ovarian physiology and function, the regulation of AMH remains poorly understood.', 'The objective was to determine whether gonadotropins acutely regulate serum AMH in women with PCOS and normal women.', 'We conducted a prospective study to compare ovarian responses to FSH in two groups of women.', 'The study was conducted in a General Clinical Research Center in a tertiary academic medical center.', 'Women with PCOS (age, 18-35 yr; n = 16) and normal ovulatory controls (age, 18-35 yr; n = 11) were recruited for study.', 'Serum samples were measured over a 24-h period after an iv injection of recombinant human FSH (150 IU).', 'Serum AMH responses after FSH administration were measured.', 'Basal serum AMH levels were markedly increased in women with PCOS compared with levels observed in normal women. After FSH injection, PCOS women failed to demonstrate changes in circulating AMH over 24 h. A similar lack of alteration in serum AMH was observed in normal women.'] Are serum anti-mullerian hormone concentrations altered by acute administration of follicle stimulating hormone in polycystic ovary syndrome and normal women?