Between-Ovary Interaction in the Regulation of Follicle Growth, Corpus Luteum Function, and Gonadotropin Secretion in the Primate Ovarian Cycle. I. Effects of Follicle Cautery and Hemiovariectomy during the Follicular Phase in Cynomolgus Monkeys

To examine the role of between-ovary interaction in the regulation of folliculogenesis in the primate ovarian cycle, the dominant follicle was ablated on day 8, 9, or 10 to interrupt the menstrual cycle, and one ovary was removed concurrently to restrict the locus of new follicle growth. Ablation of the largest visible follicle, alone or along with the ipsi- or contralateral ovary, elicited stereotypical responses; the expected midcycle surges of gonadotropin secretion were abolished and the next preovulatory gonadotropin surges occurred about 2 weeks after follicle ablation. Removal of the contralateral ovary alone had no manifest effect. The findings indicate that 1) in cynomolgus monkeys, as in rhesus, the dominant follicle had been selected by the midfollicular phase and no other follicle was available as a surrogate for a timely midcycle ovulation; 2) the time course of new follicle growth culminating in a single ovulation after follicle ablation was unaffected by the acute removal of one ovary and the concomitant restriction of the locus of new follicle growth; 3) the next follicle destined to ovulate was not selected until after the removal of the dominant follicle; 4) in the presence of the dominant follicle, the contralateral ovary contributes little, if at all, to the regulation of gonadotropin secretion, contralateral follicle growth, or subsequent contralateral corpus luteum function; 5) the hegemony of the dominant follicle is not limited to follicles of the ipsilateral ovary but extends, in some manner, to follicles of the contralateral ovary as well; and 6) unlike bilateral ovulators, a compensatory rise in gonadotropins after unilateral ovariectomy in this primate is conditional on the ovary removed and the surety of the dominant follicle.