Effect of unilateral ovariectomy at three stages of the estrous cycle on the activity of the remaining ovary and pituitary gland.

Abstract

An experiment was conducted on 63 crossbred gilts to study the effects of 6 days of unilateral ovariectomy on ovarian and pituitary gland activity when one ovary was removed at days 1, 7 and 13 of the estrous cycle. The weight of follicular fluid in the right ovary was increased significantly by removal of the left ovary 6 days earlier. This increase was not as great during the first interval (days 1 to 7) as during the second (days 7 to 13) or third (days 13 to 19). The number of large follicles (dia.≱8 mm.) was also increased by unilateral ovariectomy, and this increase was greater in the second and third intervals. The number of small follicles (dia.<8 mm.) was increased slightly during the first interval by unilateral ovariectomy, but their number decreased during the second and third. Residual FSH and LH activity in the pituitary gland varied with the stage of the estrous cycle. FSH activity was affected significantly by unilateral ovariectomy since removal of one ovary at day 7 prevented the rise in FSH from day 7 to 13 that occurred in the intact animals. Average CL weight and progesterone concentration in the CL were not affected significantly by unilateral ovariectomy.