Uteroovarian Pathways and Maintenance of Early Pregnancy in Rhesus Monkeys1

Abstract

To evaluate the possibility that corpus luteum (CL) maintenance may be regulated by the local transfer of materials from the uterus to the ovary near the time of implantation in primates, rhesus monkeys were laparotomized on Days 17-18 of pregnancy and all anatomical connections between the ovary bearing the CL and the uterus were severed. This technique was designed to prevent local uteroovarian transfer while maintaining ovarian blood flow via the ovarian artery and vein. Sham ligated animals (n = 2) maintained pregnancy; however, based on serum concentrations of progesterone and macaque chorionic gonadotropin (mCG), 4 of 6 experimental females aborted within 48 h following surgery. Abortion in the experimental animals suggested that either 1) a local uteroovarian pathway was involved in the maintenance of early pregnancy or 2) that the loss of the blood supply to the ovary from the uterine artery had a detrimental effect on CL function. To determine which of these conclusions was correct, a second experiment was conducted. Monkeys were laparotomized on Days 13-14 of pregnancy and the uterine vein was ligated at the utero-vaginal and utero-tubal junction of the uterus on the side ipsilateral (n = 4, experimental) or contralateral (n = 2, control) to the ovary bearing the CL. Sham ligation on the ipsilateral side (n = 2) was also performed. Experimental treatment was expected to block a local uteroovarian pathway while not compromising ovarian arterial blood flow. All animals maintained pregnancy. We conclude, therefore, that a local uteroovarian pathway is not required for maintenance of early pregnancy in the rhesus monkey.