Glossary · Anatomy

Vaginal epithelium

Definition: The vaginal epithelium is the stratified squamous lining of the vagina, normally rich in estrogen receptors. Premenopausal estrogen maintains a thick, glycogen-rich epithelium that supports lactobacillus colonization and acidic vaginal pH. Estrogen withdrawal at menopause thins the epithelium, depletes glycogen and lactobacilli, and raises pH — the basis of GSM.

Detailed definition

The vaginal epithelium is a non-keratinized stratified squamous epithelium that responds to estrogen. Premenopausally, estrogen maintains a thick (15–30 cell layers) epithelium with glycogen-rich superficial cells. Glycogen released as cells slough is metabolized by Lactobacillus species to lactic acid, maintaining vaginal pH at 3.5–4.5 — an acidic environment hostile to most pathogens. After menopause, with estrogen withdrawal, the epithelium thins (3–5 cell layers), glycogen content drops, lactobacilli decline, vaginal pH rises to 5.5–7.0, and the flora shifts toward gram-negative organisms including E. coli. The thinned epithelium is more friable, less elastic, and produces less natural lubrication. These changes underlie all the local symptoms of GSM and the increased UTI risk in postmenopausal women.

Why it matters in menopause

Vaginal estrogen reverses the epithelial atrophy directly: epithelium re-thickens, glycogen returns, lactobacilli recolonize, pH normalizes — typically over 6–12 weeks of treatment. This is why vaginal estrogen produces such reliable improvement in GSM and reduces UTI recurrence.

Sources

External references: Wikipedia.

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