Slavkin H C, Cummings E, Bringas P, Honig L S
Prog Clin Biol Res. 1982;85 Pt B:249-59.
The mechanisms by which epithelial-mesenchymal interactions result in differentiation are not known. A number of recombinations between vertebrate tissues associated with epidermal organs (e.g. skin, feather, mammary gland, salivary gland, tooth organ) indicate that regional mesenchymal specificity is instructive for determination and differentiation of epithelial phenotypes. In epidermal organs within which mesenchyme becomes determined and differentiates into a unique phenotype, such as during tooth organogenesis and odontoblast differentiation. Does the epithelial-derived basal lamina regulate mesenchymal differentiation into odontoblasts and the expression of dentine extracellular matrix? Experiments were designed to test the hypothesis that murine or avian epithelial-derived basal lamina possess information which is instructive for determined dental mesenchyme to differentiate into odontoblasts. The strategy was to examine homologous and heterologous tissue recombinants between Theiler stage 25 C57BL/6 molar tooth organs and Hamburger-Hamilton equivalent stage 22-26 Japanese Pharoah quail mandibular processes. Trypsin-dissociated molar epithelium and mesenchyme, reconstituted, secreted a basal lamina within 8 hours and mesenchyme differentiated into odontoblasts and formed dentine matrix within 3 days. Isolated trypsin-dissociated mesenchyme did not differentiate in vitro, whereas heterologous recombinants between odontogenic mesenchyma and quail epithelia resulted in odontoblasts and dentine production. Mouse tooth or quail mandibular epithelia served to regulate odontogenic mesenchyme differentiation. EDTA-dissociated mouse molar mesenchyme, in the absence of epithelium but with adherent basal lamina, routinely differentiated into odontoblasts. Control tooth organs routinely formed both dentine and enamel extracellular matrices within 7-10 days in our serumless, chemically-defined organ culture system. Regulation of determined mesenchymal cells to differentiate into functional and highly specialized odontoblasts appears to be mediated by epithelial-derived basal lamina and is not species or organ-specific.
上皮-间充质相互作用导致分化的机制尚不清楚。一些与表皮器官相关的脊椎动物组织（如皮肤、羽毛、乳腺、唾液腺、牙器官）之间的重组表明，区域间充质特异性对上皮表型的确定和分化具有指导作用。在间充质被确定并分化为独特表型的表皮器官中，比如在牙器官发生和成牙本质细胞分化过程中。上皮来源的基膜是否调节间充质向成牙本质细胞的分化以及牙本质细胞外基质的表达？设计实验来检验这一假设，即小鼠或禽类上皮来源的基膜具有指导已确定的牙间充质分化为成牙本质细胞的信息。策略是检查第25期Theiler阶段的C57BL/6磨牙器官与Hamburger-Hamilton等效的第22 - 26期日本法老鹌鹑下颌突之间的同源和异源组织重组体。经胰蛋白酶解离的磨牙上皮和间充质重新组合后，在8小时内分泌基膜，间充质在3天内分化为成牙本质细胞并形成牙本质基质。分离的经胰蛋白酶解离的间充质在体外不发生分化，而成牙间充质与鹌鹑上皮之间的异源重组体则产生成牙本质细胞并形成牙本质。小鼠牙齿或鹌鹑下颌上皮起到调节成牙间充质分化的作用。在没有上皮但有附着基膜的情况下，经乙二胺四乙酸（EDTA）解离的小鼠磨牙间充质通常会分化为成牙本质细胞。在我们无血清、化学成分明确的器官培养系统中，对照牙器官通常在7 - 10天内形成牙本质和釉质细胞外基质。已确定的间充质细胞向功能性和高度特化的成牙本质细胞分化的调节似乎是由上皮来源的基膜介导的，且不具有物种或器官特异性。
