Ultrastructure of granular materials in rat incisor enamel organ at early maturation stage

With scanning electron microscopy, globules were seen in inter-cellular spaces between ameloblasts with ruffled borders and papillary cells at early maturation stage. Numerous globules were located on longitudinal folds between parallel ridges on the sides of ameloblasts, but only a few in the papillary layer. In previously-scanned specimens sectioned for transmission electron microscopy, the globules were composed of finely granular material. Vacuoles containing material identical to extra-cellular granules were observed in intra-cellular portions of the ameloblasts and papillary cells.