Involvement of the Cervix in Sperm Transport Failures in the Reproductive Tract of the Ewe

Abstract

One hundred parous ewes were assigned to the following five groups, and each ewe was mated naturally during estrus: 1) untreated controls; 2) treated by subcutaneous injection with 20 µg of estradiol-17β at the time of mating; 3) treated on Day 10 of an estrous cycle with 10 mg of prostaglandin F2α (PG) to cause premature regression of corpora (ewes were in estrus and were mated on Day 12); 4) treated during an estrous cycle with 60 mg of medroxyprogesterone acetate (MAP) in an intravaginal sponge inserted at Day 8 and removed at Day 25 (ewes were in estrus and were mated on Day 27 or 28); 5) treated with a plastic spiral intrauterine device (IUD) inserted by surgery into one uterine horn (ewes were mated at an estrus occurring at least 2 wk after surgery). Ten ewes from each group were killed at 2 h and ten at 22 h after mating. The cervix (divided into three segments of equal length), uterus and oviducts were flushed and sperm cells counted. At 2 h after mating, the numbers of sperm cells recovered from the anterior cervix (geometric means in millions for Groups 1 through 5, respectively) were 2.3, 2.5, 0.3, 0.3 and 0.2 (P<0.01). At 22 h, the numbers (geometric means in thousands) recovered from the oviducts were 16.5, 6.7, 0.5, 0.3 and 0.1 (P<0.01). In three groups of ewes, partial inhibition of sperm transport into the anterior cervix was followed by partial failure of sperm transport into the oviducts.