In which location does a fertilized egg implant in horses?

The correct answer is the uterus. In equine reproduction, once the egg is fertilized, it travels from the oviduct into the uterus, where it will implant in the uterine lining. This implantation occurs approximately 6 to 8 days after fertilization, allowing the embryo to receive nutrients and ongoing support necessary for growth and development throughout gestation.

The oviducts are involved in the initial stages of reproduction, such as the transport of the egg and sperm, but they are not the site of implantation. The ovaries are where the eggs are produced and released but are also not involved in the implantation process. The cervix serves as a passageway and has various functions in protecting the uterus and maintaining pregnancy but does not play a role in the actual implantation of the fertilized egg.

Thus, the uterus is the only location among the provided choices where a fertilized egg successfully implants and develops into a fetus.