CONTEXT

In polycystic ovary syndrome (PCOS), an increased proportion of follicles leave the primordial (resting) pool and initiate growth. However, there is little evidence for a reduced reproductive life span (early menopause) in women with PCOS, suggesting that the dynamics of follicle growth, and of follicle loss by atresia, is altered in PCOS.

OBJECTIVE

The aim of this study was to investigate the possibility that loss of preantral follicles by atresia is reduced in PCOS, leading to prolonged follicle survival.

DESIGN

We compared follicle growth in normal and polycystic ovaries using cultures of small ovarian biopsies.

SETTING

Tissue samples were obtained at routine laparoscopy from 12 patients with anovulatory PCOS and 16 controls and processed in an ovarian physiology laboratory.

MAIN OUTCOME MEASURES

We performed morphometric analysis of follicle population in tissue fixed at time of biopsy (d 0) or after 5, 10, or 15 d in culture. Analyses included assessment of follicle and oocyte diameter, number and proportion of primordial and growing follicles, and number and proportion of atretic follicles.

RESULTS

In tissue fixed on d 0, the proportion of healthy growing follicles was, as expected, greater in ovaries from PCOS patients than in normal ovaries (64 vs. 28%; P = 0.0005), but there were no differences between PCOS and normal tissue during culture. The rate of atresia throughout the period of culture in follicles was, however, significantly lower in PCOS tissue (P < 0.0001). After culture, 80% of follicles in normal ovarian tissue were atretic compared with 53% in PCOS biopsies.

CONCLUSION

Follicles from polycystic ovaries demonstrate a decreased rate of atresia in culture, suggesting a mechanism for maintaining a larger follicle pool throughout reproductive life.