rat 53 Rats 50 animal experiment 35 Female 34 Rats, Inbred Strains 32 Animal 31 female genital system 31 in vitro study 25 Uterus 24 nonhuman 22 Castration 21 Uterine Contraction 21 Prostaglandins E 20 Animals 19 In Vitro 19 Prostaglandins F 19 Support, Non-U.S. Gov't 19 prostaglandin 19 Prostaglandins 18 endocrine system 18 uterus 18 Male 17 animal cell 17 indometacin 16 prostaglandin f2 alpha 16 drug efficacy 14 prostaglandin e2 14 Dinoprost 13 uterus contractility 13 Dinoprostone 12