appendix of the epididymis appendix of the epididymis the appendix of the epididymis (or pedunculated hydatid) is a small stalked appendage (sometimes duplicated) on the head of the epididymis. it is usually regarded as a detached efferent duct. appendix of the epididymisthe right testis, exposed by laying open the tunica vaginalis (appendix of epididymis labeled at center right)detailsprecursorwolffian ductidentifierslatinappendix epididymidisanatomical terminology this structure is derived from the wolffian duct (mesonephric duct) as opposed to the appendix testis which is derived from the müllerian duct (paramesonephric duct) remnant.