ヒト歯周炎罹患歯肉におけるメルケル細胞の分布および形態と神経支配について

― 特に炎症との関連における解析 ―

抄録

Oral mucosal Merkel cells are known to show polymorphism, but the biological significance of the polymorphism is not clear. To determine the biological significance, we analyzed effects of inflammation on numerical density, external figure and innervation of Merkel cells in human gingival mucosae from patients with chronic periodontitis by means of immunohistochemistry and electron microscopy. It was found that mildly inflamed gingival areas usually contained abundant Merkel cells and peripheral nerve fibers in their epithelia, whereas severely inflamed areas contained only small numbers of cells and nerve fibers. Merkel cells in mildly inflamed areas showed a high degree of polymorphism, and only oval- and round-shaped Merkel cells were in contact with nerve terminals. There were a number of Merkel cells atypically located in the prickle to granular cell layers in the mildly inflamed area. These results suggest that Merkel cells transiently disappear from gingival epithelia as a result of nerve fiber atrophy caused by severe inflammation but that these structures are regenerated as the inflammation abates. Electron microscopy revealed that some Merkel cells in the mildly inflamed epithelium make contact with lymphocytes and Langerhans cells. From these findings, it was speculated that some Merkel cells play a role in initiation or termination of gingival inflammation via the modulation of these cells.