Abstract
1. Antibody occurs in the uterus and can be withdrawn by irrigation. Intrauterine antibody results from the introduction of antibody into the lumen of the uterus.2. Neither free antibody nor the sensitization of the uterus has been produced by intramuscular injection of antigen, even when antibody has circulated in the bloodstream for periods from a few weeks to many months.3. Active sensitization of the uterus follows upon the repeated introduction of antigen into the uterus.4. It is concluded that antibody can be produced locally by some of the cells in the uterus when T. foetus antigen is present.5. The uterus of the cow can be sensitized passively in vivo by the instillation of bovine anti-trichomonas serum so that the instillation 6–10 days later of Trichomonas antigen will produce the characteristic local anaphylactic reaction.