THE FUNCTIONAL-ANATOMY OF THE URETEROVESICAL JUNCTION

Objective To obtain a new insight into the anti-reflux mechanism of th e ureterovesical junction by studying the topographical anatomy of the juxta- and intravesical meter and its relationship to the surrounding bladder musculature. Materials and methods Fresh pig bladders were fi xed, frozen and serially sectioned. Enzyme histochemistry was performe d to demonstrate tissue acetyl- and butyryl- (non-specific) cholineste rase. Smooth muscle cells were identified by immunohistochemistry usin g a monoclonal anti-alpha actin smooth muscle antibody. Three-dimensio nal computer reconstructions of the different muscle groups of the bla dder and ureterovesical junction were generated. Results On the basis of expression patterns of the cholinesterase isozymes, five different groups of muscles were identified: the detrusor, the muscularis mucosa e of the bladder, the muscle layer of the intravesical ureter and the separate inner and outer muscular layers of the pelvic meter. Conclusi on No separate ureteric sheath was identified. There appeared to be fe w or no (muscular) connections between the meter and the bladder muscu lature. The muscle layer of the meter ended beneath the mucosa of the bladder, without extension into the trigone. The submucosal section of the meter was very short, although its length was thought to be of im portance in the anti-reflux mechanism. Examination using enzyme histoc hemistry demonstrated a muscularis mucosae in the bladder which was ab sent from the trigone.