Estrous and non-estrous rabbits were inoculated with E. coli or Streptococcus pyogenes, and the mixture of the two organisms, and bacterial count and histopathological studies of uterine horns were made to observe the effects of estrogen on the resistance of the uterus to bacterial infection. The results obtained were summarized as followings;
1. Four hours after inoculation of bactoria into uterine horn, the number of organisms was significantly lower in estrous rabbits than in non-estrous regardless of the kind of organisms inoculated.
2. The highest reduction rate of the organisms among the three bacterial inoculation groups was found in estrous rabbits inoculated with E. coli, and the lowest reduction rate was with Streptococcus pyogenes.
3. Histopathological changes of uterine horns induced five days after bacterial inoculation were observed. In estrous rabbits, a mild inflammatory reaction was found in Streptococcus pyogenes group, but a slight inflammatory reaction and only a negligible inflammatory reaction were observed in mixed bacteria group, and in E. coli group respectively. In non-estrous group, however, a marked inflammatory reaction was observed in Streptococcus group, a moderate inflammatory reaction and a slight inflammatory reaction were observed in the mixed bacterial group and E. coli group, respectively.
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