ELECTRON MICROSCOPY OF THE AMELODENTINAL JUNCTION DURING EARLY DEVELOPMENT OF THE MOLARS OF HAMSTERS

¹ University of Alabama Medical Center, Birmingham, Ala.

1. Electron micrographs were prepared of developing molars of newborn hamsters.

2. First indication of amelodentinal junction is a very delicate interface between the enamel epithelium and the odontoblasts.

3. An amelodentinal membrane forms on the dentinal side of the interface and odontoblasts differentiate before the ameloblasts become columnar.

4. Forming ameloblasts are separated from the fibrillar amelodentinal membrane by a complete double cellular membrane which later breaks up and disappears. Between the odontoblasts and the amelodentinal membrane, however, the boundary is incomplete, and this is tentatively identified with the so-called terminal bar apparatus.

5. Preliminary observations on the older ameloblasts suggest a syncytiallike arrangement.