| Abstract: | Phagocytic cells in the taste buds of rat circumvallate papillaeafter the sectioning of bilateral glossopharyngeal nerves wereexamined by electron microscopy and immunohistochemistry. Electronmicrographs taken 1 day after denervation revealed that flat-shapedcells were present just beneath the taste buds and that theircellular processes extended toward the debris from the degeneratingtaste buds. At 2–6 days after denervation, long and thinprocesses of the flat cells surrounded the debris and appearedto have taken them up into the cytoplasm as small vesicles.Evidence for phagocytosis by the flat cells was seen up to 9days after denervation and again at 24 and 40 days, in correlationto the degeneration and regeneration of the taste buds. Pre-embeddingimmunohistochemistry using anti-vimentin antibody showed thatflat cells strongly reacted with vimentin. Light microscopicimmunohistochemistry using anti-macrophage antibodies (ED1,ED2) showed that throughout the post-operative days macrophageswere not present underneath or within the taste buds. Most ofthe ED2-immunoreactive resident macrophages were located inthe deep layer of connective tissue, and a few were found inthe nerve bundle. ED1-immunoreactive cells were seen in theduct cells of von Ebner's glands and a few were in the trenchwall of circumvallate papillae; however, they were also immunoreactivefor anti-OX62 antibody, which recognizes dendritic cells. Theresults indicate that the phagocytic cells of the taste budsare fibroblasts, not macrophages. Moreover, resident macrophagesparticipate in phagocytosis of degenerated nerves together withSchwann cells. Chem. Senses. 21: 467–476, 1996. |
