The mesonephric duct (also known as Wolffian duct, archinephric duct, Leydig's duct and nephric duct) is a paired organ found in mammals including humans during embryogenesis. Wolffian structures are male urogenital structures that include the epididymis, vas deferens, and seminal vesicles that differentiate from this structure.The mesonephric duct connects the primitive kidney, the mesonephros, to the cloaca and serves as the anlage for certain male reproductive organs.