Bladder Neck Muscle Degeneration in Patients with Prostatic Hyperplasia

To improve understanding of the variations of bladder neck musculature we investigated histological changes of the bladder neck associated with prostatic hyperplasia in adult male cadavers.

We examined histological sections from 24 donated male cadavers with a mean age of 74 years. Sections were subjected to Azan and immunohistochemical staining using desmin and S-100 antibodies. The collagen content per cross-sectional area was calculated and statistically compared.

The existence of 3 muscle layers (submucosal longitudinal muscles, circular bladder neck muscles and external longitudinal muscles) was confirmed at the anterior and posterior regions of the bladder neck. Increased prostate volume significantly correlated with an increase in collagen fibers and thinning of muscle bundles in the anterior bladder neck. An increase in prostate volume and increasing age significantly correlated with degeneration of the posterior bladder neck muscles. As prostatic hyperplasia advanced the bladder neck muscles were progressively affected by fibrosis with the circular muscle fibers becoming thin and fragmented. In addition the severity of fibrosis associated with prostatic hyperplasia showed interindividual variation. We also devised a schematic classification of bladder neck morphology in men.

Degeneration of muscle bundles in the bladder neck of men with prostatic hyperplasia was confirmed. It was found that the bundles became thinner along with an increase in collagenous tissue. Our schematic classification of bladder neck morphology in men may be useful for further investigations.