[Ultrastructure of the distal ureter in congenital malformations in childhood].

Ultramicroscopical examinations were performed in ten children with reflux or obstructive megaureter. Resected parts of ureters were used for investigation in connection with reconstructive procedures. Whereas in case of an obstructive megaureter an intramural and juxtavesical localised functionless narrow ureteral segment is characterised by "nexus close contacts" and dissociation of muscle cells with interposition of fibrous tissue, progredient pathonexual changes in the sense of a reversible nexus-distension and irreversible nexus-rupture were seen in megaureters with reflux. Dissociation of muscle cells is combined with typical epithelial and adventitial pathological structures. In congenital megaureter, disturbances in the electric syncytium occur in connection with nexus injury, followed by pathological innervation. Interruption of muscle autonomy and innervation in the wall structure of such congenital ureteral malformations play an ominous role in the sequence of pathogenetic factors.