Slide #180 [Vagina, human, H&E]. The vaginal wall consists of three principle layers: mucosa, muscle and adventitia. The vaginal mucosa, which may be thrown into folds (rugae) , is lined by a stratified squamous, non-keratinizing epithelium, the thickness of which may vary with the reproductive cycle. The epithelial cells are rich in glycogen (thus, the 'empty' appearance of these cells in routine histological preps), which serves as a metabolic substrate for the commensal bacteria of the vagina. The epithelium is supported by a loose to moderately dense fibroelastic connective tissue stroma with abundant venous and lymphatic vessels. Note the absence of mucous glands in the vaginal wall. The muscle layer consists predominantly of smooth muscle fibers which run in spiral-like and longitudinal fashion through the wall. Skeletal muscle fibers from the perineal musculature may also blend with the wall, though not in this particular section.