animal cell animal tissue nonhuman controlled study 111 Article 106 animal experiment 105 male 86 animal model 76 mouse 72 Animals 71 animal 67 unclassified drug 48 female 45 human 40 metabolism 38 rat 38 Mice 34 protein expression 33 Male 30 adult 29 in vivo study 29 Humans 28 genetics 24 immunohistochemistry 24 gene expression 22 in vitro study 22 Rats 20 drug effect 20 histopathology 19 human cell 19