Cell death of taste buds in the circumvallate papillae after section of the glossopharyngeal nerves.

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Apoptotic cells in the taste buds of mouse circumvallate papillae after the sectioning of bilateral glossopharyngeal nerves and the treatment with colchicine (inducer of microtubules depolimerization) were examined by the method of DNA nick-end labeling (TUNEL), together with standard electron microscopy. The taste buds decreased in number and size 3-11 days after denervation and disappeared at 11 days. The TUNEL method revealed only a few positively stained nucliei in normal taste buds but, in those of mice 1-5 days after denervation, the number of positive nuclei had increased to 3-5 times that of taste buds from normal mice. Electron-microscopic obsevation after denervation demonstrated taste bud cells containing codensed and fragmentary nuclei in a cytoplasm with increased density. The colchicine treatment after 15 hours and 1 day showed many TUNEL-positive nuclei and the condensed and fragmentary nuclei in the taste bud cells.The results show that taste bud cells under normal conditions die by apoptosis at the end of their life span, and that gustatory nerve sectioning and colchicine treatment cause apoptosis of taste bud cells.