APOPTOSIS IN MOUSE TASTE-BUDS AFTER DENERVATION

Apoptotic cells in the taste buds of mouse circumvallate papillae afte r the sectioning of bilateral glossopharyngeal nerves were examined by the method of DNA nick-end labeling (TUNEL), together with standard e lectron microscopy. The taste buds decreased in number and size 3-11 d ays after denervation and disappeared at 11 days. The TUNEL method rev ealed only a few positively stained nuclei in normal taste buds but, i n those of mice 1-5 days after denervation, the number of positive nuc lei had increased to 3-5 times that of taste buds from normal mice. El ectron-microscopic observation after denervation demonstrated taste bu d cells containing condensed and fragmentary nuclei in a cytoplasm wit h increased density. The results show that taste bud cells under norma l conditions die by apoptosis at the end of their life span, and that gustatory nerve sectioning causes apoptosis of taste bud cells with ta ste buds decreasing in number and ultimately disappearing.