Summary. In basal conditions, progesterone concentrations were similar in the ovarian veins of the ovary +CL (3211 ± 526 ng/ml) and the ovary −CL (3165 ± 554 ng/ml), but after blocking the blood flow between the ovary +CL and the uterus, the progesterone values in the vein draining the ovary −CL decreased to 1218 ± 394 ng/ml (P < 0·01), When [3H]progesterone was injected in the ovary +CL, the radioactivity appeared earlier and more concentrated in the vein draining the ovary −CL (30 sec, 0·53% of injected dose) than in the femoral vein (150 sec, 0·08% of injected dose). Removal of the ovary +CL was followed by a brief maintenance of peripheral progesterone within luteal-phase levels. The in-vitro progesterone production by a suspension of cells isolated from the corpus luteum was 47·5 ± 12·8 ng/ml/2 h, whereas luteal-like cells isolated from the ovary −CL secreted 14·3 ± 6·0 ng/ml/2 h (P < 0·01) into the medium. We therefore suggest that the symmetrical and high secretion rate of progesterone by the ovaries of the capuchin monkey indicates a between-ovary communication system, and that the luteal-like tissue of the ovary −CL can produce relatively large amounts of progesterone.
Keywords: capuchin monkey; luteal phase; ovarian vein; progesterone