Temporal Relationship Between Follicular Development, Ovulation, and Ovarian Hormonal Profile in the Capuchin Monkey (Cebus apella)

Abstract

Concentrations of estradiol [E2] and progesterone [P] in peripheral plasma were determined around the periovulatory period in the capuchin monkey (C. apella) and the results related to follicular development and ovulation as established by direct observation of the ovaries during serial laparoscopic examinations. In monkeys in which the cycle studied was defined as ovulatory based on hormonal and laparoscopic findings, a well defined E2 peak with values ranging from 473.6-615.0 pg/ml was observed preceded by 10-24 h the occurrence of ovulation. The E2 peak was followed within 12 h by a rise in plasma P reaching values of 12-15 ng/ml 24 h after the peak. P levels before the E2 surge ranged between 2.1-7.3 ng/ml. The site of the developing follicle in the ovary of these monkeys could be identified 4 days before ovulation and the gradual growth of the follicle to a maximum preovulatory diameter of 10-12 mm cold be traced laparoscopically. Ovulation was preceded by vascular changes in the follicular surface and by the establishment of the follicular cone. The time of ovulation was characterized by an intimate adherence of the internal surface of the fimbria to the follicular surface. Postovulatory changes in the ovary of Cebus monkeys were less consistent than those occurring before ovulation. Two divergent forms of luteal regression were observed and the risk of misinterpretation of such structures is discussed.