Structural changes in the aging submucosa: new morphologic criteria for the evaluation of the unstable human bladder

Biopsies from continent human bladders, ranging in age from six weeks to 95 years, were examined ultrastructurally to establish the organization of the submucosa. The submucosa was found to have a distinct organizational pattern. Collagen fibers are bound into fascicles with arborizing intercollagenous channels. These channels form an intricate network throughout the submucosa. With age, the fascicles separate into individual fibers and there is a commensurate widening of the intercollagenous channels. This process is accelerated in obstruction. As aging occurs, the channels progressively fill with an electron-dense fine particulate matter of unknown origin. The collagen reorganization and accumulation of extracellular matrix particles is thought to alter the permeability and compliance of the submucosa and to encroach upon the neurovascular bundle. A baseline set of morphologic criteria describing the natural history of the continent aged bladder is offered as a framework for future group identification in the incontinent patient.