Physiological and immunocytochemical evidence for a new concept of blood flow regulation in the corpus luteum.

To explain the high rate of blood flow in the corpus luteum, we hypothesize that luteai blood vessels offer minimal resistance to flow and are incapable of vasomotion. This hypothesis was tested in rabbits at midpseudopregnancy by measuring blood flow in the corpus luteum and ovarian stroma with tracer-labeled microspheres at three levels of arterial blood pressure, which was manipulated by constricting the aorta above the ovarian artery. In addition, the distribution of vascular smooth muscle in the ovary was evaluated with morphological and immunocytochemical techniques. Decreases in arterial pressure were paralleled by reductions in bloodflow in the corpus lutewn, whereas ovarian stromal bloodflow was unchanged. Consistent with our hypothesis, there was no change in the low level of vascular resistance offered by blood vessels in the corpus luseum,