belt-like zones, corresponding to the parazone or the diazone of the Hunter-Schreger bands.Reversed images of scanning electron-micrographs of the exposed surfaces of the developing enamel revealed round and bulb-like profiles of Tomes' processes at early amelogenesis and its changes into a characteristic structure combined with flat secretory and enclosing nonsecretory faces that dictated the orientation of corresponding enamel prisms.The results suggest that the groups of enamel prisms oriented in sideward directions first appear as small island-like specks near the enamel-dentin junction, which later merge and form alternating horizontal belt-like zones as a consequence of morphological changes of the Tomes' processes. However, the mechanisms whereby the functional grouping of secretory ameloblasts with similarly oriented Tomes' processes is induced are yet to be determined.

No abstract

No abstract

No abstract

Enamel covers the dentin in mammalian teeth. It is believed that the enamel structure reflects the function of teeth, since the enamel structure is different depending on an animal's feeding habits. Tooth germ transplantation is a popular method for developmental and tissue engineering research. However, there is little information about the structure of the enamel of transplanted tooth germ, although tooth structure, especially enamel structure, is very important for the function of teeth. In this study, the enamel structure of E13.5 mouse mandible first molars transplanted into the kidney capsule was observed by scanning electron microscopy. Many part of the tooth crown are formed at transplantation 7 day. Although enamel and dentin were observed at the cusp portion, hard tissue was not formed at the cervical portion. The enamel prisms were observed at day 21 after transplantation. The enamel was divided into three layers according to the running pattern of the enamel prisms as normal tooth germ in vivo. However, the width of the various layers was different. It seems likely that the microenvironment surrounding tooth germ may play an important role in determining the structure of the enamel, since normal tooth germ grows in the calcified alveolar bone according as development.