Interovarian communication for the control of follicular growth and corpus luteum function in the cebus monkey

We have investigated the role of the utero-ovarian ligament (UOL) in the alternating ovulatory performance of the ovaries in the capuchin monkey. In intact animals, the ovulation rate was near 90%, with 67.5% of ovulations occurring in the left ovary. Sectioning the UOL in any phase of the cycle decreased the ovulation rate by 40%, and restricted ovulations to the ovary still connected to the uterus by the UOL. Estradiol and progesterone levels were significantly reduced throughout the following cycles in treated monkeys. Removal of the ovary that had been disconnected 18-20 months previous, restored both the ovulation rate and normal steroid levels. Histological study of the UOL revealed the presence of arteries, veins, lymph vessels, and nerves. Electrical stimulation of the UOL was followed by an abrupt discharge of estradiol by the ovary bearing the follicle, advancing ovulation which was followed by a normal luteal development. Conversely, stimulation of the ovary bearing a corpus luteum did not modify either the ovarian or the peripheral levels of ovarian steroids. The UOL ligament appeared to be functional for products arising from the uterus. The distribution and effects of hCG injected intrauterinely depended upon the day of the luteal phase. In the early luteal phase, hCG was distributed symmetrically between both ovaries, and increased the progesterone secretion by the ovulatory ovary only. In the late luteal phase, hCG was preferentially distributed to the ovulatory ovary, and increased the progesterone secretion by both ovaries. The present findings provide evidence for a local mechanism, throughout the UOL, controlling both the alternation of ovulation and the transfer of substances originating in the uterus that regulate the ovarian function in primates. © 1994 Wiley-Liss, Inc.