2003 年 28 巻 3 号 p. 171-179
The life span of Merkel cells (MCs) in normal epitheha is not known During the course of a previous study we found that the numerical density of MCs in the postrugal field (PRF) of the rat hard palate is very low in adults compared to juveniles We also noticed that PRFs of premature rats contain many ectopic MCs in epithelial surface layers It is of interest to know whether the reduction of MC density in PRFs is related to expansion of the area of PRFs or to the disappearance of MCs from the epithelium, and also whether the ectopic MCs mean cell turnover accompanied by apoptosis Therefore, we examined changes of numbers and numerical densities of MCs in PRFs of rats of various days of age Apoptosis of ectopic MCs was examined by a fluorescence nick end labeling combined with mmunohistochemistry for anti-cytokeratm 18 It was found that MCs in PRFs are reduced not only in numerical density but also in number during prematuration stages of rats There were no MCs that had a nucleus with nick end label, not only in surface layers but also in basal layers of PRF epithelium It was concluded that a large number of MCs are lost from epitheha of growing rat PRFs by desquamation and apoptosis is probably irrelevant to this phenomenon.