Appendix epididymis: A small cystic projection from the surface of the epididymis which represents a remnant the embryologic mesonephros.

The epididymis is a structure within the scrotum attached to the backside of the testis. The epididymis is a coiled segment of the spermatic ducts that serves to store, mature and transport spermatozoa between the testis and the vas (the vas deferens).