Effect of tunicamycin on glycogen accumulation in the stratum intermedium and odontoblasts of rat incisor.

Repeated injection of rats with tunicamycin over two days induced a 1- to 5-fold increase in glycogen. This accumulation occurred in the stratum intermedium of the enamel organ and in young secretory odontoblasts. In rats injected over 3 days, the number of glycogen particles was at least 10 times larger than in control rats, and large glycogen accumulations were observed in the cytosol of these two groups of cells. These results were obtained by staining with periodic acid-thiocarbohydrazide and silver proteinate, a specific method for the detection of glycoconjugates containing vic-glycol groups. The existence of a relationship between these local cytosolic accumulations of glycogen and the developmental stage of certain groups of cells was shown by the changes that occurred in glycogen distribution. The present results suggest that the stratum intermedium supplies energy for precursor transport.