The persisting mesonephric duct: high junction of vas deferens and ureter.

We describe 9 examples of a rare congenital anomaly in which the unduplicated ureter joined the vas and exhibited long persisting mesonephric ducts that resembled the ureter rather than the vas. Some of the kidneys were unexpectedly well developed. It is proposed that a cranial ectopic ureteral bud may have induced a metanephric kidney in the region of the mesonephros or the ectopic bud and the metanephric blastema were displaced cranially.