Anatomy and Histology of the Lower Urinary Tract

Abstract

The function of the lower urinary tract is basically storage of urine in the bladder and the at-will periodic evacuation of the stored urine. Urinary incontinence is one of the most common lower urinary tract disorders in adults, but especially in the elderly female. The urethra, its sphincters, and the pelvic floor are key structures in the achievement of continence, but their basic anatomy is little known and, to some extent, still incompletely understood. Because questions with respect to continence arise from human morbidity, but are often investigated in rodent animal models, we present findings in human and rodent anatomy and histology. Differences between males and females in the role that the pelvic floor plays in the maintenance of continence are described. Furthermore, we briefly describe the embryologic origin of ureters, bladder, and urethra, because the developmental origin of structures such as the vesicoureteral junction, the bladder trigone, and the penile urethra are often invoked to explain (clinical) observations. As the human pelvic floor has acquired features in evolution that are typical for a species with bipedal movement, we also compare the pelvic floor of humans with that of rodents to better understand the rodent (or any other quadruped, for that matter) as an experimental model species. The general conclusion is that the "Bauplan" is well conserved, even though its common features are sometimes difficult to discern.

Vulnerability of continence structures to injury by simulated childbirth

“…For example, Sievert et al (46) used a 22 Fr. Foley catheter with 5-ml distension volume in rats weighing ϳ250 g. A study comparing induced stretch in the rat with that of a woman in labor was not within the scope of this study, and it has not been done previously, primarily because the pelvic structure of the rat is dramatically different than the pelvic bone in humans (27,40), so that comparable stretch will cause different levels of damage due to differential impact of the pelvic bone.…”

The receptor antagonist picotamide inhibits adrenergic and thromboxane-induced contraction of hyperplastic human prostate smooth muscle

“…These tissues were obtained from the periurethral zone, while most prostate tumors are located to the peripheral zone (25,29). Indeed, malignancy was not detected in our tissues upon macroscopic inspection during sampling.…”

“…Tissues in our study were exclusively taken from the periurethral zone. Most prostate tumors are located to the peripheral zone (25,29). Consequently, the extent of malignant areas (if any) in our samples may be neglected.…”

Inhibition of smooth muscle force generation by focal adhesion kinase inhibitors in the hyperplastic human prostate

“…Patients provided informed written consent for use of their prostate tissues. Tissues were taken from the periurethral zone, as most prostate tumors are located to the peripheral zone (31,34). Tissue samples did not exhibit histological signs of neoplasia, cancer, or inflammation.…”