The corpus luteum of the rhesus monkey during late pregnancy.

Abstract

Corpora lutea of pregnant monkeys were marked with india ink 20 days after fertilization. Subsequent laparotomies at 40, 100 and 155 days of pregnancy revealed that regression in size and/or vascularity of the corpora lutea occurred between 20 and 100 days of gestation. This regression was followed by a rejuvenation in size and/or vascularity of the corpora lutea between 100 and 155 days of gestation. Progestin and progesterone concentrations in peripheral, ovarian and uterine venous plasma were measured by competitive protein binding. Ovarian plasma at day 155 of pregnancy contained 14 times as much progesterone as peripheral plasma and 8 times more progesterone than uterine plasma samples. The data clearly indicate that the corpora lutea of early pregnancy are the same corpora lutea seen 2 weeks prior to parturition in the monkey. Moreover, the corpora lutea of late pregnancy are functional, as judged by ovarian venous progesterone concentrations. Endocrinology 91: 665, 1972)