Lehmann R, Slavkin H C
J Craniofac Genet Dev Biol. 1984;4(1):47-57.
Patterns of cell division have been examined in the proliferative cervical loop tissues of fetal rabbit incisor tooth organs. Evaluation of the distribution patterns of silver grains, resulting from the incorporation of [3H]-thymidine into newly synthesized DNA within tooth organs in vitro, resulted in identification of two proliferation centers: (1) an inner center consisting of inner enamel epithelial cells (i.e., preameloblasts) and predontoblasts ; and (2) an outer center consisting of outer enamel epithelium and adjacent mesenchyme. In contrast to the classically held description of epithelial cell differentiation during tooth morphogenesis, our data suggest that outer enamel epithelial cells do not migrate around the cervical loop and do not provide progenitor cells for subsequent ameloblast cytodifferentiation. During tooth development, epithelial and mesenchymal cells, which arise from either an inner or outer proliferative center, migrate in distal directions relative to the proliferative sites. Therefore, the progenitor cells for ameloblasts and odontoblasts were found to be localized in the inner proliferation zone. The implications of these findings regarding the development of continuously erupting rabbit and rodent incisor tooth organs are discussed in the context of a model.
已对胎兔切牙器官增殖性颈环组织中的细胞分裂模式进行了研究。通过评估[3H] - 胸腺嘧啶核苷掺入体外牙器官新合成DNA后产生的银粒分布模式，确定了两个增殖中心：（1）一个内部中心，由内釉上皮细胞（即成釉器前体细胞）和前成牙本质细胞组成；（2）一个外部中心，由外釉上皮和相邻间充质组成。与牙齿形态发生过程中上皮细胞分化的传统描述相反，我们的数据表明，外釉上皮细胞不会围绕颈环迁移，也不会为随后的成釉细胞分化提供祖细胞。在牙齿发育过程中，源自内部或外部增殖中心的上皮细胞和间充质细胞相对于增殖部位向远端迁移。因此，发现成釉细胞和成牙本质细胞的祖细胞位于内部增殖区。在一个模型的背景下讨论了这些发现对持续萌出的兔和啮齿动物切牙器官发育的意义。
