Effects on Parturition in the Rat of Ablation of Different Lobes of the Hypophysis. ∗

Summary

1. Ablation of posterior and intermediate lobes of the hypophysis either before conception, or on 12th day of gestation resulted in no disturbances in duration of pregnancy, in parturition or in onset of dactation. 2. Removal of anterior lobe of the hypophysis had the same effects on pregnancy and parturition as did total hypophysectomy. After both types of operation 25% of the rats delivered normally at term; 75% had a prolonged pregnancy (1 to 3 days) and either delivered late, resorbed, or died in an effort to deliver. 3. Terramycin injections given on the first and second days following hypophysectomy, decreased post-operative mortality, resulted in a larger percentage of normal deliveries, and in a smaller fatality rate at parturition as compared with non-injected animals.