Anti-Mullerian hormone (AMH) is expressed in the ovary, in granulosa cells (GC) of preantral and antral follicles. Mice lacking the AMH gene show an increase in the proportion of early growing follicles and a reciprocal decrease in the primordial pool, suggesting an important role in early follicle growth. Little is known about the expression of AMH in the human ovary. Recent studies have shown that the proportion of follicles entering the growing pool is increased in PCO, similar to that in the AMH-null mouse. The aim of this study was to examine the pattern of follicular expression of AMH protein, by immunohistochemistry, in normal and polycystic ovaries (n=24), using a highly specific AMH antibody. Sections were obtained from archived paraffin-blocked ovarian tissue (with ethical committee approval), from 8 subjects with normal ovaries, 6 with PCO and anovulatory cycles (anovPCO) and 10 with PCO and regular cycles (ovPCO). The number of follicles staining positively for AMH was assessed. In each type of ovary there was positive staining in GC from the primordial stage onwards but there was an increase in AMH protein expression with increasing follicle size, with all small antral follicles being AMH positive. There were however significant differences between types of ovary in AMH expression in preantral follicles. A significantly lower proportion of follicles at primordial, transitional and primary stages stained positive for AMH in PCO than in normal ovaries and this difference was most obvious in anovPCO (e.g. primordial: normal, 79% positive; ovPCO 72%; anovPCO 52%, p<0.0001). Thus AMH is expressed in the human ovary at all stages of follicle growth and (in contrast to the mouse) in resting, primordial follicles. The reduced expression of AMH in primordial and early growing follicles is consistent with the hypothesis that AMH deficiency may contribute to abnormal follicle dynamics in PCOS. This work was supported by MRC and Wellbeing.
22 - 24 Mar 2004
British Endocrine Societies