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uberon

sperm duct, vasa deferentia

The continuation of the archinephric duct, now called the deferent duct, extends caudally to the cloaca or to the part of the mammalian urethra that is derived from the cloaca.[well established][VHOG]

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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. 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. 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. 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.

• spermatic cord

• deferent duct artery

• epididymis

• ejaculatory duct

• deferent duct vein
• mucosa of deferent duct
• vas deferens epithelium
• muscular coat of vas deferens
• adventitia of ductus deferens