What is the role of the uterine horns?

The role of the uterine horns is to facilitate the development of the embryos in species that possess a bicornuate uterus, like many mammals, including horses. The uterine horns are the extensions of the uterus that allow for the attachment and growth of the embryos after fertilization occurs in the oviducts. This means that once the eggs have been fertilized, they migrate from the oviducts into the uterine horns, where they implant themselves into the uterine lining and begin development.

While the other options mention related functions, they do not accurately reflect the primary purpose of the uterine horns. For instance, they do not store eggs, but rather serve as the site for implantation and development post-fertilization. The connection to the vagina is also not relevant to the function of the uterine horns, as their primary purpose is related to the reproductive process occurring after fertilization rather than facilitating the passage of sperm or other reproductive functions. By facilitating implantation, the uterine horns support the continuation of pregnancy, which is crucial for species propagation.