Uterine Motility of the Ewe during the Estrous Cycle

The changes in the frequency and extent of uterine contractions during the estrous cycle were studied visually in conscious ewes, either by laparotomy or by endoscopy. The uterine body showed no appreciable motility during any stage of the cycle. Rhythmical uncoilings and coilings at similar frequencies were observed in the uterine horns during estrus and a period of about 24 hr. before and after it. During pro- and metestrus only that part of the horn next to the uterotubal junction uncoiled and coiled, during estrus in about 30% of the contractions the entire horn did so. During diestrus the horns were in a coiled position, and no movements occurred. It was suggested that the occurrence of uterine motility before and after sexual receptivity may be used to determine the time limits of proestrus and metestrus.