Urethrovaginal Septum: A Histological Study on a Cadaver and Its Clinical Significance.

The academic literature concerning the tissue bridging the anterior vaginal wall and the posterior urethral wall, the urethrovaginal septum, is lacking and inconsistent, not only when compared to non-reproductive anatomy but also when compared to male reproductive anatomy. This knowledge gap must be addressed, given the implication of this tissue in numerous female reproductive pathologies and functions, including pelvic organ prolapse, intercourse and orgasm, urethral strictures, vaginal cancers, and stress urinary incontinence. This study seeks to characterize the histological composition of the urethrovaginal septum, including type I and III collagen proportions, elastin content, neurovascular distribution, and smooth muscle arrangement. Specimens were resected bilaterally from the bisected pelvic region of a postmenopausal female cadaver, spanning antero-posteriorly from the lumen of the urethra to the lumen of the vagina. The specimens were divided into medial and lateral portions, sectioned, and stained with hematoxylin and eosin, trichrome, reticulin, and elastin stains. Images were obtained through virtual microscopy. Type I collagen was confirmed as the major connective tissue component. Reticular fibers were mainly limited to blood and lymphatic vessel walls, as well as the perineurium and epineurium of nerve fibers. The elastic fiber content was minimal, appearing mainly in the lamina propria and vascular walls and interspersed with type I collagen in the connective tissue matrix of the septum. Smooth muscle bundles were mainly observed in the muscularis layers of both walls, but to a greater extent in the anterior vagina. These findings largely confirm those of the few published histological studies of this tissue while contributing to the current state of knowledge regarding the distribution of elastin and reticulin. Further research in premenopausal females and increased awareness of the microanatomy of the urethrovaginal septum is advised.