Effects of X-lrradiation on Cell Kinetics of Oral Epithelium in Mice

Abstract

The acute radiation effects on the tongue and lip mucosa epithelium were cytokinetically investigated after the local irradiation at the head part of C₃Hf/He mice with single dose of 516 mC/kg (2000R) of X rays. The microautoradiographic study was performed for these two kinds of oral epithelium at various times after the pulse-labeling with ³H-thymidine, which followed immediately after the irradiation. The cell kinetics of irradiated as well as unirradiated basal cells were investigated by observing the changes in frequencies of the labeled cells and the labeled mitoses in the epithelium along the time course after irradiation.
The results of the analysis of the percent frequencies of mitotic cells as a function of time after the labeling and the irradiation showed that the movement of the labeled cells were blocked at G₂ phase for about 6 hr and that the cell cycle time after the 1st post irradiation mitoses became shorter than that of the unirradiated cells. However, no change was found in the migration rate of the tongue epithelium, i.e., the time required for labeled cells to migrate from basal cell layer to prickle-granular cell layer. On the other hand, only 25% of labeled cells in the lip mucosa epithelium migrated into prickle-granular cell layer until 40 hr after irradiation, and it was hardly observed that the labeled cells moved into mitotic phase.
These results suggest that basal cell of the lip mucosa is more radiosensitive than that of the tongue epithelium.