Yamamoto Hitoshi, Kim Eun-Jung, Cho Sung-Won, Jung Han-Sung
Division in Anatomy and Developmental Biology, Department of Oral Biology, Research Center for Orofacial Hard Tissue Regeneration, College of Dentistry, Brain Korea 21 Project for Medical Science, Seoul 120-749, Korea.
J Electron Microsc (Tokyo). 2003;52(6):559-66. doi: 10.1093/jmicro/52.6.559.
Tooth morphogenesis is a well-known developmental system related to epithelial-mesenchymal interactions. In mice, the dental epithelium has the potential to induce tooth formation prior to the bud stage, whereas this potential shifts to the dental mesenchyme from the dental epithelium. The reaggregation of mesenchymal tissue leads to previous memories of individual cells being reset, which is useful for studying the predetermination of mesenchyme. Here, the mesenchyme was triturated into single cells after separation of the epithelium and the mesenchyme. These single cells were repelleted and combined with the epithelium. The reaggregated tooth was transplanted into a mice kidney capsule. In order to investigate the essential functions of both the dental epithelium and the dental mesenchyme regarding their mutual interaction, a reaggregation system was introduced using the late bud stage of the mouse first molar. Amelogenin expression was examined to confirm the cytodifferentiation in the reaggregated tooth. The results showed that a new tooth formed after reaggregating the dental mesenchyme. This tooth contained enamel, dentin, dentinal tubules and dental pulp. The inner enamel epithelium of the reaggregated tooth differentiated into ameloblasts. Immunohistochemistry for amelogenin was observed both in the ameloblasts and the enamel. However, the structure of the enamel was different from that of the normal tooth, with the thickness of the predentin becoming wider. These findings suggest that reaggregated dental mesenchyme cells can produce a tooth. The fate of dental epithelium was not affected by reaggregated dental mesenchyme, although the dental mesenchyme appears to lose the information from the dental epithelium.
牙齿形态发生是一个与上皮-间充质相互作用相关的著名发育系统。在小鼠中，牙上皮在芽期之前具有诱导牙齿形成的潜力，而这种潜力从牙上皮转移到牙间充质。间充质组织的重新聚集导致单个细胞的先前记忆被重置，这对于研究间充质的预先决定是有用的。在此，上皮和间充质分离后，将间充质研磨成单个细胞。这些单个细胞重新沉淀并与上皮结合。重新聚集的牙齿被移植到小鼠肾囊中。为了研究牙上皮和牙间充质在相互作用方面的基本功能，利用小鼠第一磨牙的晚期芽期引入了一种重新聚集系统。检测釉原蛋白表达以确认重新聚集牙齿中的细胞分化。结果表明，重新聚集牙间充质后形成了一颗新牙。这颗牙齿包含釉质、牙本质、牙本质小管和牙髓。重新聚集牙齿的内釉上皮分化为成釉细胞。在成釉细胞和釉质中均观察到釉原蛋白的免疫组织化学染色。然而，釉质的结构与正常牙齿不同，前期牙本质的厚度变宽。这些发现表明重新聚集的牙间充质细胞可以产生一颗牙齿。尽管牙间充质似乎失去了来自牙上皮的信息，但牙上皮的命运并未受到重新聚集的牙间充质的影响。
