Sperm death and inhibition of sperm transport in the cervix of ewes in estrus after removal of the corpus luteum-bearing ovary.

Regulation of estrus in the ewe with prostaglandin or progestogen causes death of sperm in the cervix and inhibits sperm transport through the cervix at the regulated estrus. Because removal of the corpus luteum (CL) alters the estrous cycle, experiments were conducted to determine the effect of removing the CLbearing ovary on sperm survival and transport in the cervix at the ensuing estrus. In the first experiment, the ovary bearing the CL was removed from each of 45 unilaterally ovulating ewes on day 3, 10 or 15 of the estrous cycle (day 0 = first day of estrus). Fifteen ewes from which the non-CL-bearing ovary was removed on day 15 served as controls. Time from surgery until estrus averaged 2.1 to 2.5 days per group. At estrus, each ewe was mated to two rams and necropsied 2 hr later. Sperm were washed from the oviducts, uterus and anterior, middle and posterior one-thirds of the cervix and counted. Removal of the CL-bearing ovary (CLX) decreased (P<.01) the number of sperm recovered, particularly in the anterior one-third of the cervix, where sperm numbers averaged 1.55 million in control ewes, 40,000 in ewes CLX on day 10 and 330,000 and 220,000 in ewes CLX on day 3 or 15. In the next experiment, the CL-bearing ovary was removed from each of 18 ewes on day 10 or 14 of the cycle. Ten ewes from which the non-CLbearing ovary was removed on day 15 served as controls. Time from surgery to estrus averaged 2.0 to 2.3 days per group. At estrus, ewes