The concentrations of estradiol (E2

The concentrations of estradiol (E2) and progesterone
(Pro) were determined in conditioned media by
radioimmunoassay using a commercially available
estradiol kit (Union Medical and Pharmaceutical
Technology Tianjin Ltd., China) and a progesterone
kit (Chemclin Biotech Co., Ltd., Beijing, China), respectively.
The incubation mixture consisted of 0.2 ml
of 125I-E2 or 125I-Pro, corresponding to 0.2 ml of E2 (or
0.1 ml of Pro) standard solution containing 0, 5, 25,
100, 300, 750, or 2000 pg·ml