Polycystic ovary syndrome (PCOS) is the commonest cause of anovulatory infertility in women, but its aetiology is poorly understood. There is evidence for a primary disorder of androgen secretion, which has its origins before puberty, but it is not clear how this may cause the characteristic ovarian abnormalities. We have developed an ovine model for PCOS to explore possible differences between the small preantral follicles of androgenised female lambs with those of normal ovaries using ovine tissue obtained from cortical biopsies. Small (approximately 5 mm3) ovarian cortical biopsies were obtained from 8 female lambs that had been exposed to androgens in utero from embryonic day 30 to 90 of a 147 day pregnancy and 7 control female lambs at 8 months of age. The tissue was fixed and then mounted in paraffin, serially sectioned at 5 micrometers, stained and examined microscopically. The number of follicles were identified and recorded along with its stage of development. There was a lower percentage of primordial follicles in androgenised females (46.3% vs 65.7%; chi square p<0.001) but a higher percentage of primary follicles (50.3% vs 33.2%; chi square p<0.001) compared with controls. There was no significant difference in the percentage of secondary, preantral or antral follicles. Overall follicle density (count/mm3 tissue) was not significantly different in the two types of ovary, although there was a trend towards an increased density in androgenised females. In conclusion, there are morphological differences in small preantral follicles as a result of exposure to androgens in utero. As similar morphological differences have recently been reported in polycystic ovaries in women (Webber et al., 5th European Congress of Endocrinology 2001: Abstract O-082), it is possible that prenatal androgens provide a necessary hormonal insult for the development of this disorder. Supported by MRC.
03 - 04 Dec 2001
Society for Endocrinology