Corpus luteum maintenance in a ewe with one congenitally absent uterine horn.

During the oestrous cycle of the sheep, normal regression of the corpus luteum (cl) on Day 15 is prevented by total hysterectomy and the cycle is extended to a length approximating the gestation period (Wiltbank & Casida, 1956; Moor & Rowson, 1964). Rowson & Moor (1964) also reported that the increased life-span of the cl in partially hysterectomized sheep was roughly proportional to the amount ofuterus removed. Other experiments have demonstrated that the primary effect of theuterus on the ovary is local in nature since unilateral hysterectomy in ewes with cl in both ovaries results in the normal regression of the luteal tissue