抄録
The present study was carried out to investigate on the time of each phase in cell cycle of the tooth germ cells (internal enamel epithelial cell and pre odontoblast) and the effects of X-irradiation on the cell cycle by means of autoradiographic method with tritiated thymidine. Upper incisors of rats (Wistar strain) were used as materials. Generation times were estimated to be 27.3 hours in internal enamel epithelial cells and 25.3 hours in pre-odontoblasts, respectively. Both labeling index and photographic grains per cell on autoradiograms were markedly decreased in internal enamel epithelial cells and also in pre-odontoblasts as early as one half an hour after 1,200 R of single X-irradiation.
