The plasma concentrations of testosterone and LH during the ovulation cycle of the hen (Gallus domesticus).

The plasma concentrations of testosterone and luteinizing hormone (LH) were measured by radioimmunoassay during the ovulation cycle of the hen. The baseline concentrations of testosterone were 100 to 250 pg/ml and the maximum concentration of 904 pg/ml was observed 6 h before ovulation. The possibility that testosterone is the ovarian excitation hormone which initiates the ovulation-inducing surge of LH is discussed.