CONCENTRATION OF OESTROGENS AND ANDROGENS IN HUMAN OVARIAN VENOUS PLASMA AND FOLLICULAR FLUID THROUGHOUT THE MENSTRUAL CYCLE

Abstract

SUMMARY The concentrations of androstenedione, testosterone, oestrone and oestradiol-17β were measured in peripheral and ovarian venous blood and follicular fluid of women at various stages of the menstrual cycle. The concentration of oestradiol was similar in small follicles (diameter < 8 mm) at all stages of the menstrual cycle and in large follicles (diameter ⩾ 8 mm) except during the mid- and late follicular phase when the concentration reached a peak (∼ 1500 ng/ml). The concentration of androstenedione was lowest in large preovulatory follicles at mid-cycle at a time when the secretion into the ovarian vein was markedly increased. The concentration of testosterone in large follicles (⩾ 8 mm) was unchanged during the follicular phase whereas in small follicles there was a peak at mid-cycle. The rise in the concentration of testosterone and androstenedione at mid-cycle in peripheral plasma may be due to increased secretion by the preovulatory follicle into the ovarian vein. It is suggested that the relatively low concentration of androstenedione in follicular fluid of the preovulatory follicle arises from increased aromatization by granulosa cells in the course of oestrogen synthesis.