The oviducts open into the uterine horn through the uterine '''ostium'''. This marks the site of the '''uterotubal junction'''. This junction is gradual in ruminants and pigs, but abrupt in the horse and carnivores. In the horse, the uterine ostium is located on top of a papilla, which forms a barrier against ascending infections. | The oviducts open into the uterine horn through the uterine '''ostium'''. This marks the site of the '''uterotubal junction'''. This junction is gradual in ruminants and pigs, but abrupt in the horse and carnivores. In the horse, the uterine ostium is located on top of a papilla, which forms a barrier against ascending infections. |