Fold increase in uterine weight in responding uteri. Uteri were weighed and the average fold increase in weight of responding uteri was calculated in comparison with nontraumatized control uteri of the same genotype treated with the same hormonal regimen. Numbers of determinations: WT E, PE, n = 5; WT P only, n = 3; WT ICI, n = 10; ERKO E, PE, n = 5; ERKO P only, n = 2; ERKO ICI, n = 5.