Endocrine Abstracts

An increased number of medium-sized antral follicles is one of the characteristic features of polycystic ovaries (PCO) but little is known of the preantral stages of follicle development. The aim of this work was to explore small preantral follicle development in ovulatory and anovulatory PCO and to compare it with that in normal ovaries. Small ovarian cortical biopsies were obtained with informed consent and local ethics committee approval from 27 women with PCO, 13 anovulatory and 14 ovulatory, and 22 women with normal ovaries. All the women were of reproductive age and there were no significant age differences between the groups. The tissue was fixed, paraffin embedded, serially sectioned at 5mm, stained with H and E and examined microscopically. Every follicle identified was examined in serial sections to allow accurate assessment of stage and health. The volume of tissue examined was measured and follicle density was then calculated.

Anovulatory PCO contained a higher density of follicles compared to ovulatory PCO: median 73 (interquartile range 35 to 93) versus 27 (12 to 56) follicles/mm3: p = 0.03. There were no significant differences between ovulatory PCO and normal. The percentage of primordial follicles in both types of PCO was significantly lower than in normal ovaries: ovulatory PCO 63 (45-68), anovulatory PCO 47 (19-64), normal 79 (72-87)%: p = 0.04 and 0.01. Reciprocally, the proportion of primary follicles was raised in anovulatory PCO compared to normal: 47 (36-75) versus 16 (13 to 27)%: p=0.02. There was a trend towards an increase in the proportion of primary follicles in ovulatory PCO, 33 (26-55) versus 16 (13-27)%: p = 0.06.

Thus early follicle development appears to be different in PCO compared to normal, and the disruption is more severe when anovulatory. In other words, abnormalities of early folliculogenesis may predispose to anovulation in PCO.

This work is supported by the MRC and Wellbeing.