title: Growth promotion of urothelial cells by a silk suture in the bladder walls of rats.
abstract: This study is to describe the reaction of urothelial cells to a silk suture placed surgically in the urinary bladder. Experimental rats have a single silk suture transmurally inserted in the wall and lumen of the bladder. The controls received sham operations. At various time intervals up to the 54th week, the sequence of morphologic events which took place in the bladder wall has been studied by gross and by light and electron microscopic examinations. The mucosal hyperplasia was the major finding for those sacrificed at weeks 2, 4, and 8. A single growth or multiple polypoid growths composed of well differentiated urothelial cells were found at weeks 16, 24, and 54. None of these growths were invasive. They exhibited little evidence of progressive morphologic change with time. Ultrastructurally, the tumor cells essentially showed characteristics of urothelial cells. None of the controls developed a similar urothelial growth. In conclusion, presence of a silk suture in the urinary bladder resulted in mucosal hyperplasia followed by noninvasive tumorous growth of well differentiated transitional cells. Exact mechanisms of this growth promotion by a silk suture and the potential of the growths becoming invasive neoplasms remain to be determined.
mesh_terms: D000818:Animals; D004848:Epithelium / Q000473:pathology / Q000648:ultrastructure; D006965:Hyperplasia; D008297:Male; D008854:Microscopy, Electron; D009092:Mucous Membrane / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D013537:Sutures; D001743:Urinary Bladder / Q000473:pathology* / Q000648:ultrastructure; D001749:Urinary Bladder Neoplasms / Q000209:etiology* / Q000473:pathology