STRUCTURAL-CHANGES OF COLLAGEN COMPONENTS AND DIMINUTION OF NERVES INCONGENITAL URETEROPELVIC JUNCTION OBSTRUCTION

Purpose: Three-dimensional arrangements of smooth muscle cells, collag enous component and peripheral nerves of congenital ureteropelvic junc tion (UPJ) obstruction were studied in order to clarify the pathogenet ic mechanism of interaction among these neuro-myo-stromal components. Materials and Methods: The UPJ and upper ureters were obtained from 14 patients with congenital hydronephrosis (7 intrinsic and 4 extrinsic obstruction) and 7 normal controls. Three-dimensional arrangement of e ach structural component was observed by scanning electron microscopy, and the nerve distribution was analyzed with immunohistochemistry for protein gene product 9.5. Results: The UPJ of intrinsic obstruction h ad structural features as follows. Muscle fascicles were sparse and th in. Each muscle cell was thin in diameter. Intercellular spaces were s ix to seven times wider than controls. Collagen fibrillar sheaths of s mooth muscle cells (pericellular collagen fibrils attached to the base ment membrane) were interwoven to form a dense felt-like structure aga inst thin lace-like sheaths in controls. Interstitial collagenous comp onent showed dense and compact structure against loose network of wavy collagen bundles in controls. In the muscular layer, nerve distributi on was decreased to about one-third of controls. In contrast, non-sten otic portion of intrinsic UPJ obstruction as well as materials from ex trinsic UPJ obstruction showed no structural difference as compared wi th controls. Conclusions: In the intrinsic obstruction, nerve fibers w ere depleted in the muscular layers in the ureteric walls, resulting i n dysfunction and atrophy of muscle fibers and an increase of collagen fibers in the muscle layers with abnormal accumulation of intercellul ar and interstitial collagen. These changes may disrupt the mobility o f UPJ and lead to both mechanical and functional obstruction.