A quantitative study of lamina densa alterations in hamster cheek pouch carcinogenesis

Abstract

Lesions produced by topical application of 0.5 per cent. DMBA to the hamster cheek pouch epithelium were classified as hyperplasia, dysplasia and carcinoma groups using strict histological criteria. Untreated epithelium served as a control. Tissue samples from five animals in each group were processed for electron microscopy and electron micrographs from the epithelial-connective tissue junction were obtained from 5 blocks per animal. The micrographs were subjected to stereological intersection counting to determine the relative surface (SSLD, BM) of lamina densa which was in normal relationship to the basal cell plasma membranes. Quantitative results indicated a progressive loss of lamina densa during carcinogenesis and this was accompanied by the extrusion of pseudopodia from the basal cells through the gaps. The pseudopodia were frequently related to peripheral cytoplasmic microfilaments. Quantitative data confirmed the progressive nature of this loss, with values for SSLD,BM being of the order of 98 per cent., 88 per cent., 76 per cent, and 42 per cent. for normal epithelium and for the hyperplastic, dysplastic and carcinomatous lesions respectively. The loss of lamina densa is discussed in relation to the specificity of the response and to the development of features indicative of motility in transforming cells.

Ultrastructural and cytochemical observations on 5‐fluorouracil‐induced cleft‐palate development in hamster

“…Disturbances in the integrity of the basal lamina have been observed in many pathological and experimental conditions (Pearson and Spargo, 1961;Pearson, 1962Pearson, ,1967Caulfield and Wilgram, 1962;Kubacek, 1962;Wilgram, 1967;Johnson and Fry, 1967;Frithiof, 1969;Vracko, 1972Vracko, , 1978Vracko, , 1979Nikai et al, 1971;Ericksson and Frithiof, 1972;Vracko and Benditt, 1972;Sugimoto et al, 1973;Takarada et al, 1974;Jao et al, 1978;Ingber et al, 1981;White and Gohari, 1981;Otsubo and Kameyama, 1982;Yasuzumi et al, 1983). The disturbances include irregularities in thickness, reduplication (multilayer formation), detachment from the basal cells (i.e., increased width of lamina lucida), and fragmentation.…”

Quantitative studies of hemidesmosomes during progressive DMBA carcinogenesis in hamster cheek-pouch mucosa

“…The lamina densa opposite the hemidesmosomes often appeared to be of increased electron density and thickness. During carcinogenesis (Figs 2-6) a progressive loss of lamina densa and the extrusion of pseudopodia occurred at the epithelial-connective tissue junction (as in Tarin, 1967;Woods & Smith, 1969; White & Gohari, 1981b;Smith, 1980). This was accompanied by an apparent decrease in frequency of hemidesmosomes, which became apparent in the later stages of carcinogenesis.…”

Variations in the nuclear‐cytoplasmic ratio during epithelial differentiation in experimental oral carcinogenesis

“…Basal eells were present in eontaet with the basal lamina eomplex. fn those eases where basal lamina was absent (White & Gohari 1981b) the cells in direct eontaet with connective tissue were eonsidered as basal eells. Granular cells contained keratohyaline granules.…”