Immunohistochemistry of cell adhesion molecules of developing circumvallate papillae and taste buds.

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Cell adhesion molecules (CAMs) are membrane-associated glycorpoteins that mediate cell-cell adhesive interactions. The neural cell adhesion molecule (N-CAM) sediated adhesion participates in meural development and nerve-muscle interactions. We observed the distribution of N-CAM in the taste buds of mouse circumvallate papillae by use of an immunocytochemical technique. In adult mice, nerve fibers and some elongated taste observation showed that type-III (gustatory) cells, which have afferent synaptic contacts with the nerves, were N-CAM positive in the taste buds. Taste buds of the developing mice first appeared at day 0 after birth, and then N-CAN positive cells were found in the taste buds. This result suggests that N-CAM 9s involved in formation of the synaptic contacts between type-III cells and nerves. Taste buds are known to be contacts renewed and neurally induced. At 3 days after sectioning of bilateral glossopharyngeal nerves, N-CAM positive cells were found in the taste buds as observed in controls. At 8 and 11 days after sectioning of bilateral glossophatyngeal nerves, N-CAM positive cells were found in the taste buds as observed in controls. At 8 and 11 days after sectioning, they were still observed although the number decreased. It is likely that type-III cells alwasys synthesize N-CAM for the purpose of a synaptic contact with the verves in the near future. In the other hand, in this study of electron microscopic observation by use of the fixation with tannic acid, we found lamellar bodies, characteristic of phospholipids, in the taste bud cells and taste pores. The bodies may act as a surfactant to promote the solubility of sapid materials to facilitate their adsorption to the membrane of the taste bud cells.