Microsurgical Anatomy and the Function of the Ureterovesical Junction

Song, Jae Mann; Han, Sang Won; Lee, Hae Yon; Chung, In Hyuk

Abstract

Recently, new trials for the treatment of the vesicoureteral reflux have been proposed. These trials convince us of the need to reevaluate the ureterovesical junction and to reinvestigate the role of the detrusor muscle and the ureteral sheath. We studied forty adult and five infant human bladders and distal ureters. Microscopic sections were studied, taken serially from the ureterovesical junction and adjacent urinary bladder with the hematoxylin-eosin and the Gomori trichrome staining method. The slit shaped ureteral orifice was most commonly observed ( 57.0 %). The approximate ratio of the submucosal length to the intramural ureter was 2:3. Ureteral sheath consists of smooth muscle fibers (bundles) arranged in a helical fashion and loose connective tissues which envelope the distal ureter over a 3 cm distance to the juxtavesical portion. These structures are independent from the ureter proper. The muscle bundles of ureteral sheath are of 4 types: 1. Those which extend from the outer bladder wall to the juxtavesical ureters (JVU) and, 2. continuing from JVU, these become the detrusor muscle after entering the bladder. 3. Bundles run from the JVU to the trigone, and 4. bundles run to the trigone from the mid-circular layer of the detrusor muscle. In the bladder, most roof muscle bundles of ureteral sheath run to the upper portion of the trigone after crossing the intramural ureter ventrally. Most floor bundles run to the inferolateral portion of the bladder. In infants, the deep trigone and basal detrusor muscle are relatively thicker and not compactly organized. We conclude that ureteral sheath is of detrusor muscle origin. We suggest that ureteral sheath functions as a part of a preventive mechanism with compressing the intravesical ureter by contraction in voiding and filling phase independently against vesicoureteral reflux.