THE LIFESPAN OF CORPORA LUTEA INDUCED DURING THE LUTEAL PHASE OF THE ESTROUS CYCLE IN SWINE.

A more complete understanding of the mechanisms involved in the function and maintenance of the corpus luteum would be very useful in developing more effective methods of controlling the estrous cycle in farm animals. Various types and classes of experimental animals have been utilized in an effort to define the factors causing the persistence of the corpus luteum. In swine, several different experimental approaches have been made in an attempt to extend, experimentally, the functional lifespan of the corpus luteum in non-pregnant animals. Less frequently, attempts have been made to induce premature regression. In general, the procedures used to induce premature regression have not been effective when applied to the corpora lutea of cycling swine. For example, Sammelwitz et al. (1) reported that injected progesterone would cause luteal regression in pregnant swine but not in cycling swine