The relationship between odontoblasts and pulp capillaries in the process of enamel- and cementum-related dentin formation in rat incisors

Abstract

The relationship between odontoblasts and pulp capillaries in the process of dentinogenesis was studied in rat lower incisors, both on the labial and lingual sides, using light and transmission electron microscopy. The odontoblasts showed remarkable differences from the apical to the incisal end. Near the apical end of the tooth, "immature odontoblasts", which were thought to be involved in the formation of the mantle dentin, were arranged in a single layer, and continuous capillaries were located just beneath the odontoblasts. In the middle of the tooth, "mature odontoblasts" with highly developed cell organelles and notable processes formed a pseudostratified layer; fenestrated capillaries were found between these cells close to the predentin. The height of the odontoblast layer and the rate of dentin deposition on the labial (enamel-related) side was significantly greater than that on the lingual (cementum-related) side. Near the incisal end, cementum-related odontoblasts gradually decreased in height and number to become "post-odontoblasts" that produced atubular dentin; continuous capillaries were located subjacent to the post-odontoblasts. On the labial (enamel-related) side, however, odontoblasts retained their pseudostratification; fenestrated capillaries were still observed in the odontoblast layer. No atubular dentin was formed on the labial side.

Expression patterns of nestin and dentin sialoprotein during dentinogenesis in mice

“…Matrix-producing cells increasing the expression of their nestin and Dsp are referred to as odontoblasts, and these cells are further divided into subgroups. In our previous study using continuously growing rat incisor teeth, we have divided these cells into three types: immature, mature, and post-odontoblasts, according to their morphology, the rate of dentin deposition, and their nutritional supply (the location and ultrastructure of the odontoblastic capillaries) (39). The cells beginning to produce predentin are characterized by immature features including minute projections on their distal ends and are engaged in the production of mantle dentin where no capillaries are present in the odontoblast layer.…”

“…A lower level of expression for these proteins has also been found in non-mineralized tissues such as the brain, kidney, pancreas, and salivary gland (53). Among them, the intermediate filament nestin is considered as a marker for differentiated odontoblasts in developing teeth and newly-differentiated odontoblast-like cells apimmature and mature odontoblasts (39). Rodent incisors are continuously growing teeth, for which all stages of odontogenesis-including amelogenesis and dentinogenesis-can be surveyed if the sections of the tooth are prepared from the apical end to the incisal edge (39,48).…”

“…Among them, the intermediate filament nestin is considered as a marker for differentiated odontoblasts in developing teeth and newly-differentiated odontoblast-like cells apimmature and mature odontoblasts (39). Rodent incisors are continuously growing teeth, for which all stages of odontogenesis-including amelogenesis and dentinogenesis-can be surveyed if the sections of the tooth are prepared from the apical end to the incisal edge (39,48). Recent molecular biological studies have demonstrated the existence of a niche for self-renewing adult stem cells in these rodent incisors, which is referred to as an "apical bud" (21-23, 40, 56).…”

“…Recent molecular biological studies have demonstrated the existence of a niche for self-renewing adult stem cells in these rodent incisors, which is referred to as an "apical bud" (21-23, 40, 56). Thus, continuously growing incisors are useful materials for analyzing the developmental process of dentinogenesis, although the incisal edge shows the unique feature that an inflammatory reaction is induced by the attrition of the incisal tip (39). In contrast, rodent molars are teeth with limited growth similar to human teeth.…”

Histopathological Study of Time Course Changes in PTHrP-Induced Incisor Lesions of Rats

“…The measuring points were selected based on the previous reports (Weinreb and Weinreb, 1986;Ohshima and Yoshida, 1992;Tabata et al, 1993;Yoshida and Ohshima, 1996), and the reported values comparable to those of the control animals of the present study.…”