Generation Cycle of Oral Epithelium in Mice

¹ Loyola University School of Dentistry, Chicago, Illinois

Thirty-six C₅₇ x Black mice were injected with 60 µc/0.06 cc tritiated thymidine. Groups of three mice were sacrificed at intervals of from 15 minutes through 48 hours. The mid-sagittal sections of the tongue were stained by the Feulgen method and autoradiograms prepared.

The number of labeled cells in the stratum germinativum 1 hour after injection was determined. The total mitotic count and the total labeled mitotic count for each sacrifice period was recorded.

The DNA synthesis time was estimated to require 10 hours; G2, the interval between the end DNA synthesis and prophase, 20 minutes; mitotic time, 40 minutes; rest, 89 hours. Thus the estimated generation cycle of the oral epithelium in the tongue of mice was 100 hours.