On the Developmental Process of “Ameloblast Grouping and Dancing” in the Formation of Hunter-Schreger Bands in Indian Elephant Molar Tooth Germs

Numerous investigations based on observations of the enamel structures have reported that ameloblast movement develops the arrangement of enamel prisms leading to the formation of the Hunter-Schreger bands. Cytological and immunocytological examinations of ameloblasts were also shown ameloblast motility is involved in producing the Hunter-Schreger bands and prism arrangement. However, these conclusions were based on only the enamel structures or the location of ameloblasts. In the present study, we observed direct evidence that ameloblast groups consisted of a variety of arrangements of ameloblasts, which were concerned with the zones corresponding to the Hunter-Schreger bands in the same section of Indian elephant molar tooth germ.Initially there were cell masses that appeared in the dental papilla under the undifferentiated inner enamel epithelium. In the next developmental stage, these clusters disappeared and were replaced by groups of inner enamel epithelial cells concerned with the stratum intermedium and the stellate reticulum, and finally extending to the outer enamel epithelial cells groups. These groups correspond to the various zones of the Hunter-Schreger bands.These results provide the initial signs that “ameloblast grouping and dancing” arises in the dental papilla and that the motility is produced by a harmonious and combined movement of the whole enamel organ, moving the enamel structures.