Читать книгу An Illustrated Guide to Oral Histology - Группа авторов - Страница 28

In the late bell stage, the tooth germ increases in size, and the hard tissues of the teeth start forming. The process of dentin formation is called dentinogenesis and it always precedes the process of enamel formation, i.e. amelogenesis. It is beyond the scope of this book to go into details of these processes but briefly, under the influence of inner enamel epithelium (which changes into pre‐ameloblasts), the adjacent peripheral cells of dental papilla become odontoblasts. These odontoblasts start secreting of pre‐dentin followed by dentin; this secretion stimulates pre‐ameloblasts to change into ameloblasts which start secreting the enamel matrix (which mineralizes and becomes dental enamel later). While secreting, odontoblasts move away from the secretion area, leaving behind their odontoblastic processes. Similarly, ameloblasts migrate away from dentin while secreting enamel matrix. It should be noted that the formation of these two tissues begins in the area of future cusps/incisal edges and then slopes downward. This is the stage where the commencement of root formation begins as well.