Effects of E2 treatments on OVX rats. OVX rats were treated with vehicle (corn oil, 0.1 ml) and 17β-estradiol-3-benzoate (25 μg/kg in 0.1 ml corn oil) for the oil-group and the E2-group, respectively. A, the body weight-gain rate was compared between the two groups by calculating the ratio of body weight increase each day to the weight on the first day of treatment. A significant difference appeared on the third and the fourth days (*P < 0.05). B, the mean uterus weight was compared between the two groups. Uteri were isolated after sacrifice and weighed. The weight was normalized to the body weight on the day of sacrifice. E2 treatment significantly increased uterus weight (*P < 0.05).