Effect of Unilateral Ovariectomy on the Structure and Function of the Corpora Lutea of the Pig1

This study was designed to determine the effect of unilateral ovariectomy on follicular growth, weight of luteal tissue and luteal function of the remaining ovary in nonpregnant sows. In the first experiment, 8 sows were ovariectomized unilaterally at day 1 or day 6 of the estrous cycle and autopsied on day 14 of the same estrous cycle (day 0 being designated the first day of estrus). Eight control sows were anesthetized, but not submitted to surgery, on the same days as treated sows, and autopsied on day 14 of the estrous cycle. The remaining ovary of unilaterally ovariectomized animals responded to the absence of the other ovary with an increase in the number of follicles 5–12 mm in diameter although without the formation of additional follicles, a decrease in the average weight of luteal tissue per corpus luteum, and a reduction in the progesterone content of the luteal tissue. In a second experiment, 4 sows were ovariectomized unilaterally on day 2 of the estrous cycle. Four control sows received no treatment, and all 8 sows were autopsied 14 days after the first postoperative estrus. Unilateral ovariectomy did not affect significantly the length of the operation cycle of 3 animals, but one animal formed ovarian follicular cysts and failed to return to estrus. At the first postoperative estrus, treated animals had ovulated a number of follicles not significantly different from the number ovulated by both ovaries in control animals. There was no significant difference between control and treated animals in the average weight of luteal tissue per corpus luteum, progesterone concentration, progesterone production on incubation and progesterone content of luteal tissue. (Endocrinology74: 462, 1964)