Fine Structure of the Dorsal Lingual Epithelium of the Japanese Monkey Macaca fuscata fuscata

Abstract

Filiform papillae, which were densely distributed all over the dorsal surface of the lingual body, were crown-shaped, with a central, circular area that sloped in the anterior direction and several branches that surrounded it in a semicircle from the back of the central area. Dome-shaped, fungiform papillae were scattered among these filiform papillae. At the posterior end of the lingual body, there were four circumvallate papillae. Prominent microridges and elevated intercellular borders were widely distributed in the central area of the filiform papillae and the inteφapillar region. On the surface of the branches of the filiform papillae, microridges were rarely seen. On the surface of the fungiform papillae, indistinct microridges were observed. Histologically, the dorsal lingual epithelium revealed three different regions: the epithelium on the anterior side of the filiform papillae, the epithelium on the posterior side of the filiform papillae and the inteφapillar epithelium. Whereas the basal and suprabasal cells are similar throughout, differences characterize the intermediate and surface layers. Keratohyalin granules appear predominantly in the intermediate layer in the epithelium on the anterior side of filiform papillae. In the epithelium on the posterior side of the filiform papillae, no keratohyalin granules occur and, instead, tonofibrils are prominent. The cells become significantly flattened. In the inter-papillar epithelium, no keratohyalin granules are visible, and the tonofilaments occupy almost the entire cytoplasm of most cells in the intermediate and surface layers. The cells are larger in volume in these layers.

Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle,Eretmochelys imbricata bissa

“…In this case, however, the dorsal lingual epithelium of the sea turtle is composed of stratified squamous cells, which are more protective of the inside of this organ than are stratified cuboidal cells. In fact, the composition of the lingual epithelium of the sea turtle is very similar to that of terrestrial vertebrates, irrespective of whether or not lingual papillae are present (Cane and Spearman, 1969;Farbman, 1970;Hume and Potten, 1976;Miyata, 1989, 1990;Iwasaki, 1992b;Iwasaki et al, 1992b). Further observations in numerous species are necessary to confirm the validity of our hypothesis.…”

Electron Microscopic Characterization of Filiform Papillae in the Normal Human Tongue.

“…The fine structure of lingual epithelia has been studied in various species of animals (KATO and KUSHIDA, 1965;KUBOTA et al, 1966;FARBMAN, 1970;CANE and SPEARMAN, 1969;GREENBAUM and PHILLIPS, 1974;HUMS and POTTEN, 1976;FERNANDEZ et al, 1978;SINGH et al, 1980;BOSHELL et al, 1980aBOSHELL et al, , b, 1982HOFER,1981;KRAUSE and CUTTS, 1982;STERFLICK et al, 1983;MACKENZIE and BICKENBACH, 1984;MACK-ENZIE and DABELSTEEN, 1987;OHMURA, 1988;KONDO et al, 1988;IWASAKI andMIYATA, 1989, 1990;IWASA-KI, 1990, IWASAKI et al, 1992. These studies demonstrated that lingual epithelia vary to a considerable extent in morphology among different species, showing unique external configurations represented by the presence of various types of papillae.…”

“…Shapes and structures of filiform papillae vary among different species, and it is speculated that such differences in the morphologies of filiform papillae may reflect thier phylogeny to some extent (IWASAKI et al, 1992). Although some studies reported that epithelia of filiform papillae in several kinds of mammals are not morphologically divisible into anterior and posterior areas (BOSHELL et al, 1982;STER-FLICK et al, 1983;IWASAKI and MIYATA, 1990), this study clearly demonstrates that human dorsal lingual epithelia show three distinct regions, i. e., epithelia on the anterior and on the posterior sides and the interpapillary epithelium.…”

“…Although some studies reported that epithelia of filiform papillae in several kinds of mammals are not morphologically divisible into anterior and posterior areas (BOSHELL et al, 1982;STER-FLICK et al, 1983;IWASAKI and MIYATA, 1990), this study clearly demonstrates that human dorsal lingual epithelia show three distinct regions, i. e., epithelia on the anterior and on the posterior sides and the interpapillary epithelium. Previous ultrastructural observations have indicated that filiform papillae in most mammals, including primates (IWASAKI et al, 1992), are formed in two different patterns of keratinization. Epithelia on the posterior side of papillae show hard, hair-like keratinization, while epithelia on the anterior side of papillae show soft, skin-like keratinization.…”

“…Two types of keratohyaline granules which differ in their morphogenesis are known. One type originates from the complex of tonofibrils and keratohyaline substances (FUKUYAMA and EPSTEIN, 1967), while the other originates mainly from the coagulation of ribosomes (FUKUYAMA and EPSTEIN, 1967;IWASAKI andMIYATA, 1989, 1990;IWASAKI at al., 1992). It is possible that the electron dense granules in the lower squamous layer are keratohyaline granules of ribosomal origin, and that the thickening of plasma membranes between the lower and upper squamous layer might be dependent on keratinization processes.…”