Morphological Study of the Ureterocele: a Possible Clue to its Embryogenesis as Evidenced by a Locally Arrested Myogenesis

Abstract
The wall of a ureterocele and the proximal ureter involved were investigated with light and electron microscopy. Emphasis in our study was on the muscular structure. In most cases, that is in patients with single or duplex, or simple or ectopic ureteroceles, muscle bundles were hardly developed in the dome of the ureterocele but were well developed in the proximal ureter, with and without dilatation. In the dome of the ureterocele muscle cells were much smaller than those in the proximal ureter. Thick and thin myofilaments were demonstrated in muscle cells in the proximal ureter but thick myofilaments were absent in the dome of the ureterocele. These findings may suggest that a ureterocele is a segmental embryonal arrest of the most distal portion of the ureter.