Age-Associated Collagen Remodeling in Vaginal Tissue: A Histomorphometric Analysis.

Background: The female reproductive system undergoes progressive degeneration with age, among which the imbalance of collagen metabolism in vaginal wall tissue is a key pathological feature.

Objectives: This study aims to deeply investigate the dynamic trend of collagen within the vaginal wall of women of different ages and the interrelationship of its subtype proportions, to determine whether there are age-related changes in collagen.

Methods: A total of 40 healthy women were included and divided into four groups according to age: Group A (20-30 years), Group B (30-40 years), Group C (40-50 years), and Group D (>50 years). The morphological characteristics of the mucosa were assessed through colposcopy, and histological changes in the vaginal wall were analyzed using HE, Masson, and Sirius Red staining.

Results: With increasing age, the color of the vaginal mucosa gradually changed from pink (Group A) to pale or dark red (Group D), the density of the rugae decreased, and the surface moisture decreased. Histological staining showed that epithelial thickness significantly decreased with age, and the collagen content in the lamina propria was greatly reduced. The collagen in the muscularis remained relatively stable but still showed a significant decrease after the age of 40. Sirius Red polarized light staining showed that the ratio of Type I/III collagen significantly increased with age.

Conclusions: This study systematically revealed for the first time the dynamic characteristics of vaginal wall collagen with aging, confirming that collagen in the lamina propria shows more significant loss compared to the muscularis. We found that the Type I/III collagen ratio increases in an age-dependent manner, and this imbalance in collagen subtype ratio may lead to vaginal functional decline. These findings not only provide evidence for the aging of the female reproductive system but also open up new research directions for developing precise interventions targeting collagen metabolism.