Cell Proliferation Kinetics of the Internal Enamel Epithelium of Mouse Incisors

¹ Medical Research Center, Brookhaven National Laboratory, Upton, Long Island, New York

A kinetic analysis of the proliferation of preameloblasts of mouse incisors was made from autoradiographs following tritiated thymidine administration. The minimum generation time estimated from the mitosis curve was 14.2 hours. The minimum DNA synthesis time, postsynthesis time, mitotic time, and presynthesis time were 5.5, 0.82, 0.5, and 7.4 hours, respectively. The average total generation time of 24.0 hours was calculated from the ratio of the average DNA synthesis time (7.2 hours) to the index of labeling (0.30). During the preameloblastic maturation process, four successive cell divisions were found to occur prior to the cells becoming functional ameloblasts. The minimum transit time for preameloblasts was approximately 56.8 hours.