Alteration of Corpus Luteum Function in the Cycling and Unilaterally Pregnant Pig

The relationship of the uterus and the gonadal hormones in corpus luteum regulation and in pregnancy maintenance are not understood in the pig. When one uterine horn is made sterile by severing it from the uterine body, failure of pregnancy occurs in the intact horn. Unilateral regression of the corpora lutea occurs on the side of the sterile horn while the corpora lutea adjacent to the intact horn are maintained. The mechanisms causing the unilateral regression and the pregnancy loss in the unilaterally pregnant pig are not clear. Progesterone has no effect on corpus luteum function in the cycling pig while in the pregnant pig it causes corpus luteum regression. The estrogens appear to have a luteotropic effect in the cycling pig; the limited data available indicate that they are also luteotropic in the pregnant pig. The present study involved a series of five experiments conducted to determine the relationship of the uterus and the gonadal hormones in corpus luteum maintenance in the cycling and unilaterally pregnant pig. The specific objectives are outlined for each experiment. Advisor: Dwane R. Zimmerma