The vascular cast of the human uterus: from anatomy to physiology.

The blood supply to the uterus originates mainly from the uterine artery. However, the uterine and ovarian arteries form anastomoses bilaterally. Controversy exists about the direction of the flow in the anastomoses and thus the origin of the arterial supply to the tube and tubal part of the uterus. A similar arcade is formed by the vaginal and uterine arteries. We have investigated the vascular border of supply between the uterine and ovarian arteries in postmenopausal women, which was positioned in the uterus 1-2 cm from the tube. A similar result was found in younger, ovulating women. However, the border between the territories irrigated by the uterine and ovarian arteries differs between the follicular and luteal phase; more uterine tissue is perfused from the ovarian artery when a large follicle is present. This constitutes the first description of a functionally determined shift in the territorial divide of two vascular systems and has numerous practical implications. The venous system copies the arterial one with one major exception: some of the uterine veins join the ovarian outlet. The close contact between veins and arteries facilitates transfer of substances, thus forming semilocal systems of regulation; for example, the ovary locally influences the function of the ipsilateral tube and part of the uterus. From a therapeutic point of view, it has been documented that application of progesterone to the vagina creates high uterine concentrations due to local vascular transfer.