Diurnal variations in plasma LH, progesterone, testosterone, estradiol, and estrone in the Japanese quail.

Plasma luteinizing hormone (LH), progesterone, testosterone, estradiol, and estrone of the male and female quail were determined by a radioimmunoassay. Progesterone and testosterone or progesterone and LH were determined continuously in ovulating or nonovulating female quail and male quail at 3 hr intervals throughout the day. In another set of experiments, plasma LH, progesterone, estradiol, and estrone were determined simultaneously in ovulating quail, which were autopsied at 3 hr intervals. The plasma progesterone concentration showed a peak 3 hr before ovulation and reached basal level at the time of ovulation, whereas no peak could be observed at any time in the nonovulating or male quail. The LH showed a peak 3 to 6 hr before ovulation and reached the minimum at the time of ovulation, whereas in males and nonovulating quail no specific trend could be observed. Plasma testosterone, estradiol, and estrone levels peaked at 6 hr before ovulation in ovulating quail, whereas testosterone in male and in nonovulating quail showed a peak at 1400 hr.