Studies on the potential of the dental mesenchyme for the dental regeneration

牙齿形态发生被普遍认为是研究上皮-间充质相互作用的良好模型系统。牙齿上皮有可能在小鼠的芽期之前诱导牙齿的形成。然而，这种潜力后来从牙齿上皮转移到牙齿间充质。为了阐明牙间充质的基本性质，进行了重组实验。结果表明，重组后的间充质可以形成牙齿和牙周组织。然后，进行组织重组实验，以确定潜在的诱导牙齿形成的基础。牙胚牙上皮和牙胚牙间充质之间的重组导致牙齿的形成，而牙胚牙上皮和牙间充质之间的重组则导致不能形成牙齿。由于间充质细胞不凝聚在间隔芽周围，因此牙间充质细胞具有诱导牙齿形成的能力是其基本特性，而牙芽周围则需要凝聚。此外，为了分析移植的效果，对移植牙的牙釉质进行了扫描电子显微镜观察。虽然像正常牙齿一样，釉质棱柱的运行方式将釉质分为三层，但每一层的宽度都不同于正常牙齿。微环境似乎在釉质结构的形成中发挥了作用，因为牙胚生长在钙化的骨骼中。

Tooth morphogenesis is generally considered to be a good model system for epithelial-mesenchyme interaction. The dental epithelium has the potential to induce the tooth formation prior to the bud stage in mice. However, this potential shifts later from the dental epithelium to the dental mesenchyme. To clarify the essential properties of the dental mesenchyme, reaggregation experiments were carried out. The results showed that the reaggregated mesenchyme could form tooth and periodontium. Then, tissue recombination experiments were performed to identify the basis for the potential to induce tooth formation. Recombination between the dental epithelium of the diastema and the dental mesenchyme of the tooth germ resulted in tooth formation, whereas although recombination between the dental epithelium of the tooth germ and the dental mesenchyme of the diastema resulted in failure to form a tooth. Since the mesenchymal cells did not condense around the diastema bud, dental mesenchyme has the ability to induce tooth formation as its essential properties, whereas it is necessary to condensation surround the tooth bud. In addition, to analyze the effects of transplantation, the enamel of a transplanted tooth was observed by scanning electron microscopy. Although the enamel was divided into three layers by the running pattern of the enamel prisms as in normal teeth, the width of each layer was different from that of a normal tooth. It seems likely that the microenvironment may play a role in forming the enamel structure, since the tooth germs grow inside of calcified bone.