A view on the anatomy of the ureterovesical junction.

Macro- and microscopic dissection of 8 adult and 2 fetal human bladders was undertaken in two directions as part of a study to evaluate ureterovesical junction function. In the trigonal region the detrusor muscle consists of 3, more or less triangular layers. Both ureters are only loosely enveloped by a fibromuscular sheath of mainly bladder origin. This design allows for easy movement of the ureters on their oblique course through the bladder wall. The ureteral muscle fibers play only a minor part in the sheath or join the detrusor muscle. The majority fan out to end at the bladder mucosa or intermingle with fibers originating from the opposite ureter. Since an intricate muscular structure can be demonstrated, an active anti-reflux muscular component in the normal human bladder seems plausible. A classic ureteral sphincter mechanism does not exist. Our findings are discussed and compared with data from the literature.