Local Pathway Controlling Luteal Function in the Guinea Pig

To localize the pathway of uterine luteolytic control in the guinea pig, treatment groups were subjected to unilateral surgical severance of structures linking uterus and ovary. Treatments were: (1) sham operation; (2) ovarian vessels severed cephalic to ovary; (3) complete severance between uterus and ovary; (4) severance of utero-ovarian anastomotic vessels; (5) severance of all but utero-ovarian anastomotic vessels; (6) removal of an oviduct segment; (7) severance of all but the oviduct. Surgery was performed between Days 2-5 of the cycle, and animals were autopsied upon vaginal opening or Day 20, if opening had not occurred. Ovaries were studied histologically for evidence of unilateral luteal maintenance (ovarian asymmetry) upon the operated side. No such maintenance was observed in the controls. A high incidence of asymmetry occurred in Group 3 (complete separation). A moderately high incidence of ovarian asymmetry was noted in Groups 4 and 7, in both of which the main anastomotic vessels were cut, but none occurred in Groups 5 and 6 with these vessels intact. These results indicate that the local pathway for uterine luteolysis must be within the utero-ovarian anastomotic vessels or some associated structure.