Testis
Below you can see a diagram of the testis. Sperm are produced in the seminiferous tubules in a process that takes 2 months to complete. The sperm then are moved through the seminiferous tubules to the rete testes, on to the efferent ducts and then into the single duct of the epididymis. The epididymis is composed of the head, body and tail. As sperm move through the epididymis they are modified so that they can be motile and fertilize an oocyte. In the tail of the epididymis, sperm are stored with 54 billion sperm present in the adult stallion. If a stallion does not ejaculate, he can store sperm for up to 10 days in the tail of the epididymis. During ejaculation, sperm are moved by muscle contractions from the epididymis to the vas deferens. A vasectomy is when the vas deferens is cut to sterilize a male but not reduce the production of the hormone testosterone. Castration is removal of the testes, which not only sterilizes a male but also removes the source of testosterone and reduces male aggressiveness.
