Ovarian steroid secretion in normally menstruating women I. The contribution of the developing follicle
Authors: Aedo A.-R. , Pedersen P. H. , Pedersen S. C. , Diczfalusy E. 
Published: December 2008

In 9 normally menstruating women undergoing surgical sterilization by tubal ligation the levels of a dozen steroids were measured in the blood from the peripheral and both ovarian veins before and after the enucleation of the largest follicle. In addition, the peripheral levels of progesterone, 17-hydroxyprogesterone, oestradiol and oestrone were measured during 3 pre-operative and 3 post-operative days.

Compared to their levels in peripheral blood, the levels of pregnenolone, 17-hydroxypregnenolone, progesterone, 17-hydroxyprogesterone, androstenedione, testosterone and oestradiol were significantly higher in the blood draining both ovaries, while those of oestrone were higher only in the blood draining the 'active' ovary (containing the largest follicle) and those of dehydroepiandrosterone and cortisol only in the blood draining the contralateral 'inactive' ovary. No differences were found as far as the levels of 20α-dihydroprogesterone and dihydrotestosterone are concerned. Furthermore, a comparison of the steroid levels in the blood draining the two ovaries revealed that the levels of oestradiol and oestrone were higher in the venous blood draining the 'active' ovary and those of dehydroepiandrosterone in the blood draining the 'inactive' one.

Enucleation of the largest follicle resulted in the following changes:

1) A significant drop in the peripheral oestradiol levels which was associated with a significant rise in the levels of the other steroids studied, except those of androstenedione, testosterone and oestrone, which remained unchanged. 2) Decreased levels of oestradiol and oestrone and increased levels of dihydrotestosterone and cortisol in the venous blood draining the ovary that previously contained the largest follicle. 3) No differences were any longer found in steroid levels between the blood draining the two ovaries, with the exception of cortisol levels, which were higher in the blood originating from the 'inactive' ovary. 4) The levels of 17-hydroxyprogesterone, androstenedione, testosterone, oestradiol and oestrone were higher in the blood draining both ovaries when compared to their peripheral levels. 5) The peripheral levels of 17-hydroxyprogesterone, oestradiol and oestrone dropped to early follicular phase values within 24 h and remained at that level for at least 3 days.

The results are interpreted as indicating that the principal secretory products of the largest follicle in vivo are oestradiol and oestrone. Moreover, both ovaries secrete 17-hydroxyprogesterone, androstenedione and testosterone and additional amounts of oestradiol, and most probably also some pregnenolone, 17-hydroxypregnenolone and progesterone. The relative contribution to the peripheral levels of 17-hydroxyprogesterone by the largest follicle as compared to that of other ovarian structures requires further investigation.

It is emphasized that the stress associated with surgery gradually increases the secretion of a number of adrenal steroids, that may reach the ovaries in considerable quantities. This may render difficult the assessment of the effect of the enucleation of the largest follicle on the secretion of some steroids by the ovaries.