Immunohistochemical Study on Cfokeratin Expression in Lingual Epithelium of Human Fetus

Park, Sung Sik; Yang, Yeon Sik; Bae, Geun Young; Nam, Gwang Il

Abstract

The human oral mucosa has noncornified lining epithelium, cornified masticatory epithelium, and complex epithelium. The epithelium of human tongue shows diverse morphological variations from one site to another, and conflicting reports exist in the literature concerning the type of lingual epithelium. Cytokeratin[CK] have been shown to characterize different type of epithelia. In the present study to clarify intermediate filament patterns of tongue mucosa and lingual gland in human fetus from second trimester of pregnancy and adult, cytokeratin expression was investigated immunohistochemically using antibodies for cytokeratins in the dorsal surface of tongue, taste bud, and lingual gland, and comparison with the expression between fetus and adult was made. The epithelium of the fetal lingual papillae consisted of 4 to 6 layered stratified cells, and that of the inferior surface of tongue consisted of 6-8 layered stratified cells in PAS-hematoxylin stain. The lingual gland was well differentiated and the alveolus was strongly positive to PAS reaction. The dorsal surface of the adult tongue was composed of lingual papillae. The papillae was covered by keratinized stratified squamous epithelium and interpapillary area by nokeratinized epithelium in hematoxylin-eosin stain. The taste bud was present in the fungiform papilla. The lingual gland appeared among the muscle layers near the inferior surtace and was composed of mucous and serous cells. By immunohistochemical stain, the epithelium of the lingual papillae exhibited various staining-intensities for cytokeratin antibodies, and showed same staining patterns bosh epithelium in tip of papilla and interpapillary area in fetus. However, the dorsal epithelium of the adult tongue showed different staining patterns between tip of the papilla and interpapillary area. In fetal lingual papilla CK7 and CK8 were expressed in superficial cells, AE8 in intermediate and superficial cells, CKl4 in basal cells. MNFI116 and AE3 showed a strong reaction in basal and suprabasal cells. The epithelium of the inferior lingual surface reacted positively with AE8 and CK14, MNF116, and AE3. CK7 and CK8, however, were not reacted. In adult lingual papilla CK10 was expressed in superficial cells of the tip of the papilla, AE8 in suprabasal cells of interpapillary epithelium, CKl4 in basal cells of papillary and interpapillary epithelium, CKl9 in superficial cells of interpapillary epithelium, MNFI116 and AE3 in suprabasal cells of papillary and interpapillary epithelium. However, CK7, CK8, CK18, and 5D3 were not expressed in the epithelium of the dorsal tongue. The cells of taste bud in fetus showed positive reactions for CK7, CK8, MNF116, and AE3, but negative reactions with CK10 and AE8. The cells of taste bud in adult were stained with CK7, CK8, CK18, and MNF116, but not stained with CK10 and AE8. In lingual gland of fetus, CK7, CK8, CKl8, 5D3, MNF116, and AE3 were expressed in alveolar cells. Only CK10 gave a negative staining in ductal cells. The mucous cells of the adult lingual gland were reacted with CK7, CK10, CK18, CK19, and MNF116, and the serous cell with CK7, CK19, and MNF116. The ductal cells of the adult lingual gland were stained with CK7, AE8, CK18, CKl9, 5D3, MNF116, and AE3. CK14 was expressed in the cells of intralubular ductule, not in the ductal cells. By electron microscopy, the epithelia of both dorsal and inferior lingual surfaces in fetus consisted of nonkeratinized stratified squamous epithelium. A cell with clear cytoplasm and some dense granules was noted among the basal cells. These results indicate that the epithelium of fetal lingual papillae is non-keratinized type and the epithelium of the papillary tip is keratinized type and interpapillary epithelium is nonkeratinized type in adult, and suggest that the superficial cell containing cytokeratins 7 and 8 in dorsal lingual epithelium of fetus has a similar role to the periderm of fatal skin.