Number of sperm in the oviducts, uterus, and cervix of the mated ewe as affected by exogenous estradiol.

Six experiments were conducted to determine the ability of exogenous estradiol-17/3 to increase numbers of sperm in the oviducts, uteri and cervices of inseminated estrous ewes. In a 2 x 3 factorial experiment, ewes were mated during either early or late estrus; ewes in each group were either not treated or were treated with estradiol by subcutaneous injection once, at 6 hr after mating (30 /ag of estradiol), or twice, immediately before mating (30/ag) and 6 hr after mating (10 ~tg). Ewes were necropsied 24 hr after mating, and sperm were recovered from the oviducts, uterus, and anterior, middle, and posterior segments of the cervix. Two estradiol injections, before and after mating, increased sperm numbers significandy (P=.02) in the anterior one-third of the cervix; one estradiol injection, after mating, had no apparent effect. In a 3 x 2 factorial experiment, ewes were in natural unregulated estrus or were in regulated estrus either after induced regression of corpora lutea with prostaglandin F2t~ or after administration of medroxyprogesterone acetate by intravaginal sponge. Estradiol (30 /ag) was injected subcutaneously into one-half of the ewes immediately before mating. Ewes were necropsled 24 hr after mating. Regulation of estrus reduced (P<.05) sperm numbers in the anterior cervix. Estradiol t reatment counteracted the effect of regulating estrus. Estradiol did not increase sperm numbers in ewes in natural estrus or increase sperm numbers in any seg-