Ultrastructural changes of epithelium‐connective tissue junction in experimental lingual tumors

Abstract

In this study, plaque‐like lesions, epithelial hyperplasias, and papillary invasive carcinomas were produced in the tongues of hamsters by the application of DMBA combined with trauma for 16 weeks. The junction between the neoplastic epithelial cells and the connective tissue was studied ultrastructurally. In plaque‐like lesions, the basal lamina was partially decreased in both thickness and density or partially discontinuous. In epithelial hyperplasias, cytoplasmic projections were observed in the portion of the basal cell near the intercellular space, and the basal lamina was absent around these cytoplasmic projections. In papillary invasive carcinomas, however, numerous cytoplasmic projections extended from various portions of the basal surface of the basal cells into the underlying connective tissue. The basal lamina was also absent around these projections. In epithelial hyperplasias and papillary invasive carcinomas, some of the cytoplasmic projections appeared almost empty, some contained a small number of tonofilaments and ribosomes, and others were filled with a large number of ribosomes but did not contain the tonofilaments. The collagen fibrils were markedly reduced in number in the area around cytoplasmic projections. The cytoplasm of some fibroblasts in that area contained many intracellular collagen fibrils.

Tumorigenesis of the Oral Mucosa and Skin in Athymic Nude Mice: DMBA, Trp-P-2 and ENU Applications

“…However, lingual carcinoma could not be produced in any of the Groups. These results suggest that athymic nude mice are relatively similar in carcinogen sensitivity to conventional hamsters that were used in the previ-ous studies (11)(12)(13)(14)(15)(16), and are in agreement with some studies (8,9) which suggest that there are no differences in chemical carcinogenesis for either conventional or nude mice.…”

“…So far, no papers have reported on experimental oral tumor induction in athymic nude mice. In regard to experimental lingual carcinogenesis, some studies have shown that DMBA is a potent chemical carcinogen for in vivo tongue carcinogenesis (11)(12)(13). Previous studies also indicated that a combination of trauma and applications of chemical carcinogens such as DMBA, Trp-P-2 (3-amino-1-methyl-5H-pyrido [3,4-b] indole) and ENU (N-ethyl-N-nitrosourea) to hamster tongues or rat tooth germs led to the development of lingual carcinomas (14,15), lingual epithelial dysplasia (16) and odontogenic tumors (17), respectively.…”

4NQO-Induced Rat Tongue Carcinoma: An Ultrastructural Study

“…However, the ultrastructural changes have been far less studied. In regard to tongue cancer, only two studies in the English literature were published in which the carcinogenic agent was administered by topical application [7,8]. Nevertheless, Otsubo and Kameyama used 7,12-dimethylbenzo(a)anthracene (DMBA) and hamsters [7], while Jiang et al, employed 4-nitroquinoline 1-oxide (4NQO) and rats [8].…”

“…In regard to tongue cancer, only two studies in the English literature were published in which the carcinogenic agent was administered by topical application [7,8]. Nevertheless, Otsubo and Kameyama used 7,12-dimethylbenzo(a)anthracene (DMBA) and hamsters [7], while Jiang et al, employed 4-nitroquinoline 1-oxide (4NQO) and rats [8]. The main findings in these studies included presence of cytoplasmic projections of the basal and intercellular aspects of the cancer cells, considerable decrease in the number of desmosomes, occurrence of atypical cytoplasmic tonofilaments, increased intercellular spaces, and changes in the basal lamina ranging from absence to discontinuity to normal appearance and to increased thickness or multilayering.…”

Morphological Changes in the Lingual Papillae and Their Connective Tissue Cores on the 7,12-dimethylbenz[.ALPHA.]anthracene (DMBA) stimulated Rat Experimental Model

“…DMBA (7,12-dimethylbenz[α] anthracene or 9,10-dimethyl 1,2-benzanthracene) is wellknown as a carcinogenic agent and long-term stimulation of DMBA produces squamous cell carcinoma (SCC) that is similar to human oral SCC (Zhou et al, 2006). Prior to the production of carcinoma, there have been some reports regarding initial morphological changes on the epithelial and/or submucous tissues (Suzuki, 1986;Takeuchi et al, 1975;Otsubo and Kameyama, 1982 Yoshimura et al (2005) observed the three-dimensional morphological changes of CTCs of the oral mucosa amongst oral submucous fibrosis patients using SEM. After exfoliation of the epithelium, patchy degenerative areas of the connective tissue cores (CTCs) were found.…”