Where does fertilization of the egg primarily occur in horses?

Fertilization of the egg primarily occurs in the oviducts, which are the tubes that connect the ovaries to the uterus. After ovulation, when a mare releases an egg, the egg is captured by the fimbriae of the oviduct and transported into the oviductal lumen. This is where the sperm, following mating, will meet the egg and fertilization takes place.

The oviducts serve several important functions; they not only facilitate fertilization but also provide the appropriate environment for the early division of the fertilized egg before it moves into the uterus. In horses, the timing of ovulation and the lifespan of the egg and sperm are crucial, and the oviducts play a vital role in this process, making them the primary site for fertilization.