Structure of trabeculated detrusor smooth muscle in cases of prostatic hypertrophy.

The light and electron microscopic structure of biopsy samples of trabeculated urinary bladder from patients with proven outlfow obstruction due to prostic hypertrophy has been compared with the morphology of control bladder specimens. In the latter the detrusor muscle bundles were composed of smooth muscle cells closely packed together with very little intervening connective tissue. In contrast, irrespective of age, detrusor muscle from trabeculated bladders contained many muscle bundles in which the constituent cells were of relatively small diameter and were widely separated from each other by dense masses of connective tissue. No morphological evidence for smooth muscle hypertrophy or hyperplasia was obtained in the present study. In the electron microscope the connective tissue between the smooth muscle cells of trabeculated bladders was seen to contain, in addition to collagen fibrils, an extensive meshwork of electron-dense microfibrils apparently in continuity with the basal laminae of the smooth muscle cells. Regions of close approach between smooth muscle cells were seemingly unaffected by trabeculation as was the distrubution and fine structure of autonomic nerve terminals. These observations are intended to form a baseline for comparision with the results of future morphological studies of trabeculation arising in response to different aetiological factors.