The efferent ducts (or efferent ductules or ductuli efferentes or ductus efferentes or vasa efferentia) connect the rete testis with the initial section of the epididymis.There are two basic designs for efferent ductule structure: a) multiple entries into the epididymis, as seen in most large mammals. In humans and other large mammals, there are approximately 15–20 efferent ducts, which also occupy nearly one third of the head of the epididymis.