The prevalence and character of the muscularis mucosae of the human urinary bladder

We report the results of a histological evaluation of 335 consecutive autopsy specimens of apparently normal urinary bladder for the presence of a complete, partial or minimal muscularis mucosae. There were 164 females (49%) and 171 males (51%), ranging in age from 20 weeks of gestation to 102 years. A muscularis mucosae was present in 117 bladders (35%). The female to male ratio was 2:1, with 45% of female and 25% of male bladders containing a muscularis mucosae. The muscularis mucosae was complete in one case (1%), partial in 23 cases (6%) and minimal in 93 cases (28%). The occurrence of a partial or complete muscularis mucosae was ten times more likely in women than men. The presence of a muscularis mucosae in both women and men was not associated with any known disease process, nor was it related to patient age.