epididymis Epididymis 52 Male 50 nonhuman 48 rat 48 article 46 male 42 male genital system 42 priority journal 38 animal experiment 30 androgen 28 Rats 26 Animalia 24 Spermatozoa 24 animal cell 24 human 24 unclassified drug 24 Animal 22 Female 22 Support, Non-U.S. Gov't 22 fertilization 22 spermatozoon 22 Animals 20 controlled study 20 in vitro study 20 radioisotope 20 endocrine system 18 human cell 18 Testosterone 16 animal tissue 16