THE CORPUS LUTEUM OF THE SHEEP: EFFECT OF UTERINE REMOVAL DURING LUTEAL REGRESSION

Summary. The degree to which the corpus luteum is influenced by the uterus during the period of luteal regression has been investigated in two series of experiments. Ovarian vein blood was collected for proges-terone analysis and the uterus was removed from forty normal sheep(Experiment 1) and eleven superovulated animals (Experiment 2) on the 15th day after oestrus. In addition, one ovary was removed from each sheep in Exp. 2 and the corpora lutea were studied histologically. At autopsy, on either Day 18, 25, 50 or 100, further samples of ovarian venous blood and luteal tissue were obtained from those animals whose corpora lutea had been maintained. Luteal involution was arrested by hysterectomy on Day 15 even when the concentration of progesterone in the ovarian venous blood had declined to values as low as 40 \g=m\g/100ml plasma and karyorrhexis had become widespread. It is suggested that the uterus is essential both for the initiation and for the continuation of the degenerative processes that occur during regression of the corpus luteum