[A case of right duplex kidney with double ureters and left dysplastic kidney with bifid ureter]

During dissecting practice for students, a case of anomalous urinary tracts was found in a 81 year-old Japanese female cadaver which had an extraordinarily large right kidney with double ureters and a dwarf left kidney with a bifid ureter. The histological investigation on the left kidney revealed the renal dysplasia including thyroid gland-like widening of urinary tubules and the hyperplasia of interstitium. No renal corpuscles were observed besides very few primitive ones. Two ureters originating from the left kidney united each other in the proximal portions and the united ureter ran down the normal pathway to the urinary bladder. The left ureter was thin and underdeveloped but the circular and the oblique musculature were distinguished in the distal three quarters of the ureter. The right large kidney was shown to be a duplex kidney. Both the upper and the lower poles were well-developed and histologically normal except the compensatory hypertrophy of the cortex obviously resulting from the dysplasia of the left kidney. The upper and the lower pole ureters draining the duplex kidney never crossed each other and entered the bladder through adjoining two ureterovesical junctions at the normal position. The possible embryological basis for these anomalies was discussed.