A comparative light-microscopic, electron-microscopic and chemical study of human vaginal and buccal epithelium

The scarcity of sizeable specimens of normal oral mucosa for experimental p urposes has hampered research on oral epithelium. Because large specimens o f viable human vaginal mucosa are readily available and because vaginal and buccal epithelia are microscopically similar, vaginal mucosa has been used successfully to establish a human cyst model in experimental animals. The ultrastructure and distribution of keratin filaments in these epithelia are also similar, as is their permeability to water and a number of chemical s ubstances. Therefore, if vaginal mucosa could be substituted for buccal muc osa it would expedite research on the epithelium of buccal mucosa, To stren gthen further the concept that vaginal epithelium could replace buccal epit helium in certain experimental studies, the thickness of these epithelia, t heir patterns of surface keratinization, the presence or absence of interce llular lipid lamellae and their lipid contents were now compared. Thirty-th ree specimens of vaginal mucosa from postmenopausal women and 36 of buccal mucosa were investigated. To compare the thickness of the epithelial layers the number of cell layers in sections of 20 vaginal and 20 buccal mucosal specimens were counted in the three thickest and three thinnest regions of each specimen. Surface keratinization was evaluated on sections stained wit h the Picro-Mallory method. To demonstrate lipid lamellae two vaginal and t wo buccal mucosa specimens were examined electron microscopically after nor mal fixation and postfixation in ruthenium tetroxide, Following solvent ext raction of 11 vaginal and 14 buccal epithelia, quantitative lipid analyses were performed using thin-layer chromatography. No statistically significan t differences were found between the maximum and minimum number of epitheli al cell layers. The patterns of surface keratinization and the distribution and appearance of the lipid lamellae in the intercellular spaces were simi lar. The lipid composition of the two epithelia corresponded, except for th e cholesterol esters and glycosylceramides, which were higher in buccal epi thelium. Ceramides for vaginal epithelium and triglycerides for buccal epit helium were not determined. Based on structural similarities, a similar lip id composition and earlier findings, it is concluded that vaginal epitheliu m can be used as a substitute for buccal epithelium in certain in vitro, an d possibly for in vivo, studies. (C) 2001 Elsevier Science Ltd. All rights reserved.