Animals Female Rats rat 336 nonhuman 330 article 298 female 268 controlled study 254 animal experiment 244 priority journal 232 Rats, Sprague-Dawley 174 animal tissue 148 animal cell 144 animal model 94 Animalia 88 Male 88 protein expression 86 Rats, Wistar 84 Ovary 78 unclassified drug 72 Pregnancy 66 animal 60 male 58 Humans 52 Rattus 50 enzyme activity 50 apoptosis 48 cell proliferation 48 estradiol 48 progesterone 48