Local uterine regulation of the corpus luteum

In order to determine if the well known uterine inhibition of the guinea pig corpus luteum is a local effect, a series of partial hysterectomies were performed. Some groups were subjected to one‐half or three‐fourths hysterectomies alone, while in others one ovary was also removed on either the side retaining some or the side losing all uterine tissue. In addition, two groups in which all ovarian and uterine tissue was preserved were subjected to unilateral or bilateral complete surgical separation of all communicating structures between uterus and ovary. Sham‐operated, totally hysterectomized, and unilaterally ovariectomized groups were used as controls. In all groups in which an ovary left in the animal was separated from direct contact with its uterine horn, the estrous cycles became long and erratic, or were arrested completely due to the persistance of active corpora lutea in those ovaries. However, corpora lutea regressed normally in all ovaries left in their normal relationship to a uterine horn. These results indicate that the uterine regulatory factor does reach the ovary by some local route.