[Light and electron microscopic studies on experimental oral precancerous lesions. Wounding and Trp-P-2 application].

The purpose of this study was to investigate histologically and ultrastructurally the changes of epithelial cells in the tongue which was wounded twice and treated with Trp-P-2 (3-amino-1-methyl-5H-pyrido [4,3-b] indole). Light Microscopy. Hamsters were divided into 10 groups (Groups A-J). In all 10 groups, the tip (2 mm) of the tongue was excised with scissors. In Groups A and F, the wound was painted trice weekly with DMSO (dimethyl sulfoxide) for 8 weeks. In Groups B, C, D, G, H and I, the wound was painted trice weekly with a 0.5% solution of Trp-P-2 in DMSO for 8 weeks. In Groups E and J, the wound was not treated for 8 weeks. At the end of 8 weeks, in Groups A, B, C, D and E, the tip of the tongue was again excised, while in Groups F, G, H, I and J, the tip was not excised. In Groups A, C, F and H, the tongue was painted daily with DMSO until the animals were killed. In Groups B and G, the animals received no treatment until they were killed. In Groups D, E, I and J, the tongue was painted daily with Trp-P-2 until the animals were killed. Animals of all groups were killed at 11 and 15 days after the second excision or after the end of 8 weeks. The tongue was examined histologically. Electron Microscopy. In Groups a, c and d, the animals received the same treatment as those of Groups A, C and D, respectively. The animals were killed at 15 days after the second excision. The tongue was examined ultrastructurally. 1. Light Microscopic Observation. 1) In Group A, at 11 and 15 days, the tongue showed only hyperkeratosis. 2) In Group B, at 11 and 15 days, the tongue showed the changes of the mild epithelial dysplasia. 3) In Groups C and D, at 11 and 15 days, the tongue showed the changes of the marked epithelial dysplasia. These changes were disorientation of cells, cellular and nuclear pleomorphisms, nuclear hyperchromatism, increased number of mitotic figures, abnormal keratinization and elongation of epithelial projection. 4) In Group E, at 11 and 15 days, the tongue showed the changes of the mild epithelial dysplasia. 5) In Groups F, G, H, I and J, the tongue showed only hyperkeratosis. 2. Electron Microscopic Observation. 1) In Group a, the cells in the basal cell layer were round or ovoid in shape with large centrally-located nuclei.(ABSTRACT TRUNCATED AT 400 WORDS)