Cummings E G, Bringas P, Grodin M S, Slavkin H C
Differentiation. 1981;20(1):1-9. doi: 10.1111/j.1432-0436.1981.tb01149.x.
To assess the requirement for specific or possibly non-specific epithelial instructions for mesenchymal cell differentiation, we designed studies to evaluate and compare homotypic with heterotypic tissue recombinations across vertebrate species. These studies further tested the hypothesis that determined dental papilla mesenchyme requires epithelial-derived instructions to differentiate into functional odontoblast cells using a serumless, chemically-defined medium. Theiler stage 25 C57BL/6 or Swiss Webster cap stage mandibular first molar tooth organs or trypsin-dissociated, homotypic epithelial-mesenchymal tissue recombinants resulted in the differentiation of odontoblasts within 3 days. Epithelial differentiation into functional ameloblasts was observed within 7 days. Trypsin-dissociated and isolated mesenchyme did not differentiate into odontoblasts under these experimental conditions. Heterotypic recombinants between quail Hamburger-Hamilton stages 22-26 mandibular epithelium and Theiler stage 25 dental papilla mesenchyme routinely resulted in odontoblast differentiation within 3 days in vitro. Odontoblast differentiation and the production of dentine extracellular matrix continued throughout the 10 days in organ culture. Ultrastructural observations of the interface between quail and mouse tissues indicated the reconstitution of the basal lamina as well as the maintenance of an intact basal lamina during 10 days in vitro. Quail epithelial cells did not differentiate into ameloblasts and no enamel extracellular matrix was observed. These results show that quail mandibular epithelium can provide the required developmental instructions for odontoblast differentiation in the absence of serum or other exogenous humoral factors in a chemically-defined medium. They also suggest the importance of reciprocal epithelial-mesenchymal interactions during epidermal organogenesis.
为了评估间充质细胞分化对特定或可能非特定上皮指令的需求，我们设计了研究，以评估和比较脊椎动物物种间同型与异型组织重组。这些研究进一步检验了一个假设，即使用无血清、化学成分明确的培养基，已确定的牙乳头间充质需要上皮来源的指令才能分化为功能性成牙本质细胞。第25期Theiler阶段的C57BL/6或瑞士韦伯斯特帽状期下颌第一磨牙牙器官，或经胰蛋白酶解离的同型上皮-间充质组织重组体，在3天内可使成牙本质细胞分化。7天内可观察到上皮分化为功能性成釉细胞。在这些实验条件下，经胰蛋白酶解离并分离的间充质未分化为成牙本质细胞。鹌鹑Hamburger-Hamilton第22-26期下颌上皮与第25期Theiler阶段牙乳头间充质的异型重组体通常在体外3天内导致成牙本质细胞分化。在器官培养的10天内，成牙本质细胞分化和牙本质细胞外基质的产生持续进行。鹌鹑和小鼠组织界面的超微结构观察表明，在体外10天内基底膜得以重建，并且维持完整。鹌鹑上皮细胞未分化为成釉细胞，也未观察到釉质细胞外基质。这些结果表明，在化学成分明确的培养基中，无血清或其他外源性体液因子时，鹌鹑下颌上皮可为成牙本质细胞分化提供所需的发育指令。它们还提示了表皮器官发生过程中上皮-间充质相互作用的重要性。
