Pattern of ovarian steroid secretion during ovulation of in vitro perfused rat ovaries varies with method of sampling

Wistar rats were primed at 25 days of age with 20 i.u. PMSG s.c., followed 48 h later with 100 ng LH/ml to induce the ovulatory process in vitro. Assays for progesterone, oestradiol, and testosterone were performed on samples taken at fixed intervals of 0, 1, 2, 4, 8 and 12 h after LH administration. The results show that, while there was some degree of correlation in the concentrations of progesterone between the ovarian extract and perfusate, there were very large differences in the measurable amounts of testosterone and oestrogen in the fluid samples and ovarian homogenates. Therefore, taking samples from the perfusate may not provide a good assessment of the steroidogenic activity in the ovary.