Lack of regional surface differences in mouse bladder urothelium: a scanning electron microscopic study.

The surface structures of mouse urinary bladder epithelium, the urothelium, were examined in SEM. The entire surface area of both a moderately and a well stretched bladder were studied. No regional differences were found in either case. The moderately stretched bladder showed deep folds, while the well stretched bladder had only small folds giving the bladder an accordion-like appearance. In both bladders the typical surface structures were microridges arranged in a honeycomb-like pattern. The present study indicates that focal or regional differences found in bladders treated with chemicals or exposed to radiation are a result of the treatment itself, and not of differences normally occurring in the urothelium.