Ovarian function in pigs following hypophysial stalk transection or hypophysectomy

Abstract
Corpora lutea developed in pigs following hypophysial stalk transection on the day after estrus or mating. By day 12 they were smaller in unmated stalk-sectioned animals than those in mated stalk-sectioned, as well as being smaller than those in day 13 unmated or mated control pigs. At day 16 luteal progesterone concentration was lower in unmated than mated stalk-sectioned animals. By day 20 corpora lutea regressed in unmated and mated stalk-sectioned pigs. Living embryos were present in the uteri of mated stalk-sectioned animals at days 12 and 16 but only necrotic embryos were found at day 20. Graafian follicles regressed in both unmated and mated stalk-sectioned pigs. In hysterectomized animals having persisting corpora lutea, luteal regression began within 4 days and was complete by 12 days after hypophysial stalk transection. Estrogen maintained corpora lutea in intact control animals but not in pigs stalk sectioned the day after estrus or mating. Desiccated porcine anterior pituitary or human chorionic gonadotrophin maintained corpora lutea in pigs hypophysectomized after hysterectomy.