<P> Most vertebrates have some form of duct to transfer the sperm from the testes to the urethra . In cartilaginous fish and amphibians, sperm is carried through the archinephric duct, which also partially helps to transport urine from the kidneys . In teleosts, there is a distinct sperm duct, separate from the ureters, and often called the vas deferens, although probably not truly homologous with that in humans . </P> <P> In cartilaginous fishes, the part of the archinephric duct closest to the testis is coiled up to form an epididymis . Below this are a number of small glands secreting components of the seminal fluid . The final portion of the duct also receives ducts from the kidneys in most species . </P> <P> In amniotes, however, the archinephric duct has become a true vas deferens, and is used only for conducting sperm, never urine . As in cartilaginous fish, the upper part of the duct forms the epididymis . In many species, the vas deferens ends in a small sac for storing sperm . </P> <P> The only vertebrates to lack any structure resembling a vas deferens are the primitive jawless fishes, which release sperm directly into the body cavity, and then into the surrounding water through a simple opening in the body wall . </P>

Where does the vas deferens join the urethra