Epididymis

The epididymis ( /ɛpɨˈdɪdɨmɪs/; plural: epididymides /ɛpɨˌdɪdɨˈmiːdiːz/) is part of the male reproductive system and is present in all male amniotes. It is a single, narrow, tightly-coiled tube (in adult humans, six to seven meters in length) connecting the efferent ducts from the rear of each testicle to its vas deferens. A similar, but probably non-homologous, structure is found in cartilaginous fishes.