Figure 3: 5-FU-distilled water treated group: At day 8, the dorsal surface of tongue reveled atrophy and loss of the normal appearance of filiform papillae. Filiform papillae showed flattening of the tips with few shallow epithelial ridges (A1, H & E x100). Vacuolar degeneration of basal and supra basal epithelial layer were seen (A2, H & E x400). Atrophic changes in the shape of fungiform papillae and orientation of the taste bud cells were also seen, the gustatory pore appear ill defined with infiltration of inflammatory cells in the connective tissue (A3, H & E x400). At day 12, some filiform papillae were still missing but others restore its conical shape with hyperkeratosis with few shallow epithelial ridges, the shape of fungiform papillae appear similar to normal but with some cellular vacuolation (B1, H & E x10; B2, H & E x400). Negative immune reactivity to Ki-67 (C1,C2, immunohistochemistry x400) and Bcl-2 (C3,C4,immunohistochemistry x400) in tongue epithelium at day 8 and 12 respectively.