Uncommon ureteric ectopias: embryological implications

We herein report two rare ureteric ectopias, one in the uterus, the second in the rectum. These kinds of ectopias are not easily explained with regard to the classic embryological theories of the too-cranial or too-caudal origin of the ureteric bud on the mesonephric duct. We thus set out new explanations consistent with embryological studies on the narrow contact between the developing paramesonephric and mesonephric ducts, and on the so-called cloacal septation.