Regeneration ability of fungiform papillae and taste-buds in rats

We have earlier shown that the taste-bud-bearing fungiform papillae form a stable pattern on the tongue of rats. In this study the effect of removal of the fungiform papillae in rats was investigated. The fungiform papillae on a 10 × 5-mm area on one side of the tongue were removed after mapping of both sides under an operating microscope. Serial sections of five rat tongues within 1 day of biopsy showed that all but one papilla were gone. After 4, 6 and 12 months an average of seven papillae with taste-buds were found in the operated area, compared to 20, 26 and 23 in the controls. Comparison of tongue maps before and after these periods showed that papillae had not migrated from areas outside the area of the biopsies. To test the assumption that the extent of biopsy determined the amount of regeneration, only the upper part of the papillae with their taste buds were removed in 15 rats. Complete regeneration of papillae and taste buds was obtained within 14 days. The function of the regenerated taste buds was tested by bilateral recording from the chorda tympani proper nerves. No difference in response amplitudes was observed between the sides. When, however, the whole papilla including its base was removed, neither the papilla nor the taste-bud regenerated. The results show that the ability of the fungiform papilla and the taste-bud to regenerate after removal of the papilla is related to the extent of the biopsy. If the entire papilla including its base is removed, it will not regenerate. If only the upper part is removed, complete regeneration of both papilla and its taste-bud will occur.