Ureteral structure and ultrastructure. Part III. The congenitally dilated ureter (megaureter).

A selected group of congenitally dilated ureters was examined under light and electron microscopy, and the findings were compared to the clinicoradiologic features of each ureter. These dilated ureters exhibit qualitative and/or quantitative muscular deficiencies. The obstructed megaureters secondary to posterior urethral valves and the megaureters with reflux show non-specific pathologic changes in response to increased work load or decompensation but infection within the ureter is detrimental to the muscle cells. The ureters in babies with prune belly syndrome suffer from reduced muscle cell population and a distinct myopathy involving the myofilaments within the muscle cells. The dysplastic ureter is morphologically and end stage ureter wherein the muscle cells are severely compromised. Whether this is an underdevelopment or exhaustion from repeated infections is a matter for speculation.