[Follicular development in pregnancy and the polycystic ovarian syndrome]

In order to obtain some clues to the mechanism of follicular development, we studied sequential changes in circulatory hormone from spontaneous abortion up to the next ovulation in 11 women. In addition, morphological analysis of the follicles was performed in the ovarian tissue obtained from 4 pregnant women and another 4 women with polycystic ovarian syndrome (PCO). Blood was collected every 2-4 days and the serum samples were analyzed for HCG (LH), FSH, progesterone and estradiol by radioimmunoassay (RIA). Whole ovaries or the tissue obtained by ovarian wedge resection were sectioned serially at 2.5 micrometers. Every 13th slice was stained and examined under a light microscope. The present data were summarized as follows. A dominant follicle started to grow when LH.HCG levels declined to approximately 120 mIU l and FSH increased slightly. The largest nonatretic follicle seen in pregnancy or PCO was comparable with that seen in the late luteal phase of a normal cycle. The atretic rate of middle sized follicles (2.0 less than or equal to approximately less than 4.0 mm in diameter) was significantly higher in PCO than that seen in normal or pregnant women. These data indicate that the hormonal milieu of pregnancy or PCO does not interfere with the follicular development up to the stage of the largest nonatretic follicle seen in the late luteal phase of a normal cycle. This sized follicle grows to a dominant follicle within a short period under a minor stimulus by FSH.