ABSTRACT
In the female Bolivian squirrel monkey a much greater elevation of serum estradiol (E2) was measured after mating than that observed in similary cycling monkeys that did not mate. This raised the possibility that cycling squirrel monkeys may not ovulate during nonmated cycles To test this hypothesis, we performed laparoscopies on nine isosexually housed, cycling monkeys to observe the ovaries after the luteinizing hormone (LH) surge, which was measured by mouse interstitial cell bioassay using LER 1909-2 as the standard. Single ovulatory stigmas were identified as well demarcated, red, punctate depressions at the center of dome-shaped elevations on the ovarian surface in eight monkeys, when laparoscopically examined 9-56 hr after the LH peak. One monkey examined laparoscopically prior to the LH surge had a large translucent cystic follicle, confirming the morphology of the mature prevulatory follicle. Mean progesterone (P) concentrations fell to a nadir 1 day prior to the LH surge and then began to rise on the LH surge. Peak P levels were found 2 days after the LH surge. In the ovulating animals in which periovulatory E2 levels were measured, no value was greater than 800 pg/ml, indicating that the presence of follicular rupture was not sufficient to account for the elevated E2 levels observed after mating. These data confirm ovulation and follicular rupture in the absence of mating and delineate the relationship between periovulatory LH, P, and E2 secretory patterns in cycling squirrel monkeys.