Correlation of 45Ca incorporation with maturation ameloblast morphology in the rat incisor.

Rats were injected with 45Ca and horseradish peroxidase to determine the patterns of 45Ca incorporation into incisor enamel and the morphological types of the overlying maturation ameloblasts. 45Ca autoradiography showed no differences in the patterns of incorporation into enamel between routinely embedded and freeze-dried specimens. Enamel overlaid by ruffle-ended ameloblasts was much more heavily labeled while that overlaid by smooth-ended ameloblasts showed only moderate labeling. The observations lend further support to the hypothesis that the ruffle-ended cells are very active in mineralizing enamel and that the smooth-ended cells are in a passive, restorative phase.