Rats animal model controlled study nonhuman 165 animal experiment 161 rat 159 Animals 151 article 151 priority journal 114 Female 100 female 95 animal tissue 94 Rats, Sprague-Dawley 69 Male 67 Rats, Wistar 67 animal cell 66 male 61 protein expression 48 Animalia 37 unclassified drug 34 enzyme activity 33 Disease Models, Animal 30 animal 27 progesterone 26 Mice 25 immunohistochemistry 24 Animals, Newborn 22 Humans 22 Progesterone 22 Rattus 22