Which structure in the testes is primarily responsible for the production of sperm?

The seminiferous tubules are the primary structure in the testes responsible for the production of sperm. These highly coiled structures provide the site for spermatogenesis, the process by which sperm cells are produced from germ cells. Within the seminiferous tubules, both Sertoli cells and spermatogenic cells work together. Sertoli cells support and nourish the developing sperm, but they are not the direct producers of sperm. As germ cells undergo meiosis and differentiation, they develop into mature sperm, a process that occurs exclusively within the seminiferous tubules.

In contrast, other structures listed serve different roles in the male reproductive system. The epididymis is responsible for the storage and maturation of sperm after they are produced in the seminiferous tubules. The vas deferens is the duct that transports sperm from the epididymis to the urethra for ejaculation, and Sertoli cells contribute to the environment necessary for sperm development but are not themselves responsible for sperm production. Therefore, the seminiferous tubules are clearly the primary site of sperm production in the testes.