Electron microscopic localization of alkaline phosphatase in the enamel organ of the young rat

Abstract

The localization of alkaline phosphatase in the enamel organs of 1-day-old rats was investigated using the lead-citrate method introduced by Mayahara et al. (1967). The majority of enzyme activity was associated with the cell membranes of the stratum intermedium and the stellate reticulum, and with part of the cell membranes covering the proximal ends of the cells of the inner dental epithelium or the ameloblasts. The enzyme activity of those cells seemed to have occurred in a stage immediately prior to the development of the stratum intermedium. Weak enzyme activity was also observed in association with the basal cell membrane of the enamel organ in the growing end of the tooth, though no enzyme activity was observed in these zones in light-microscopic sections. Some cytoplasmic bodies seen in the cells of the stratum intermedium occasionally showed enzyme activity.