Periovulatory Progesterone Concentration in the Peripheral Plasma of the Rhesus Monkey with a Methodologic Note on the Detection of Ovulation

Abstract

Peripheral plasma progesterone concentrations were measured by competitive protein binding analysis in 23 normally cycling rhesus monkeys and related to the day of ovulation as established by direct observation during serial laparotomies. Plasma progesterone concentrations began to increase abruptly on the day prior to ovulation, reaching maximal values of approximately 4 m[mu]. g/ml 3-4 days after ovulation. On the day of ovulation some animals showed a decline in plasma progesterone concentration, others remained unchanged, and the remainder increased in continuous fashion. A rapid and simple method, based on a modification of the competitive protein binding technique for the measurement of progesterone, which permits the highly reliable determination of the day of ovulation in the rhesus monkey is described.