Figure 3.

(top) Results from representative ewes demonstrating that RU486 blocks the ability of P to inhibit the pulsatile secretion of LH. (Upper Left) Positive control ewes received vehicle followed by intravaginal P implants. (Upper Middle) Experimental ewes were injected with RU486 and received intravaginal P implants. (Upper Right) To control for any effects of RU486 per se, a third group was injected with RU486 and did not receive P implants. (Lower Left) LH pulse frequency (mean ± SEM). (Lower Right) mean level over the four 3-hr periods (mean ± SEM). LH pulses are noted by solid symbols and the shaded bars mark the period that P is present. ∗, P < 0.05; ∗∗∗, P < 0.001.