[The muscular architecture at the ureteropelvic junction in congenital hydronephrosis--a stereo-morphometric study].

Ureteropelvic junctions surgically taken from twelve patients with congenital hydronephrosis were submitted to stereo-morphometric studies on the architectural changes of smooth muscle layer. The specimens were opened longitudinally along the ureteral axis, flatly extended on a board, fixed in formalin and embedded in celloidin-paraffin. Serial histological sections in parallel with the wall were prepared; the 3D muscular architecture, visualized in some cases by computer-aided reconstruction, was simplified into vectors of bundles so that their arrangement might be expressed by a vector distribution. Deviation from the norm of architecture at the ureteropelvic junction was disclosed: Reduced muscles with increased connective tissues in four cases and disarrangement of bundles in eight cases, including two with predominantly longitudinal element, three with circular element and another three with irregular orientation. These abnormalities, probably reflecting abnormal maturation of muscles, appear to be related with the urinary obstruction in patients with congenital hydronephrosis.