Vein size in intact and hysterectomized mice during the estrous cycle and pregnancy.

The diameters of the ovarian, uterine, and femoral veins and the inferior vena cava were measured during stages of the estrous cycle in intact and hysterectomized mice and at intervals during pregnancy in mice with embryos in both uterine horns or in only the left horn. At metestrus I vein sizes were the least and were not significantly different in intact and hysterectomized mice. Ovarian and uterine veins showed the same or increased diameters at other stages of the cycle; veins enlarged progressively during pregnancy in intact mice. Non-gravid uterine horns showed little size increase as compared to gravid horns. Increases in vein diameter appeared to be correlated with local production of reproductive hormones. Evidence for transuterine migration of embryos was observed in 21 of 53 mice in which one uterine tube had been ligated or one ovary had been removed.