Hata R I, Slavkin H C
Proc Natl Acad Sci U S A. 1978 Jun;75(6):2790-4. doi: 10.1073/pnas.75.6.2790.
Mesenchymal specification of epithelial cytodifferentiation and morphogenesis has been considered to be a general feature of various epithelial-mesenchymal interacting systems (e.g., salivary gland, mammary gland, feather, hair, and tooth morphogenesis). In contrast, we have demonstrated that a mesenchyme can be induced by a heterologous epithelium to synthesize in quantity a specific gene product(s) unorthodox to the organ from which the mesenchyme was taken. Stage 22-23 avian limb bud epithelium induced 17-day embryonic mouse tooth mesenchyme to differentiate into cartilage. Peptide analysis (cyanogen bromide cleavage after purification of extracted collagen chains) demonstrated that heterologous tissue recombinations produced type II collagen alpha(II) (i.e., cartilage-type) in addition to type I collagen alpha(I)alpha(2). Intact or reconstituted mouse molar tooth organs synthesized type I collagen and type I trimer alpha(I) collagen. Immunohistochemical criteria using anti-type II collagen antibodies identified type II collagen in cartilage-like matrix within the mesenchymal component of heterologous tissue recombinants. Cartilage has never been described during in vivo or in vitro tooth tissue differentiation or associated with the pathology of dental papilla mesenchyme. These results support the hypothesis that epithelial-mesenchymal interactions during embryonic development can selectively induce de novo synthesis of unique gene products.
上皮细胞分化和形态发生的间充质特化被认为是各种上皮-间充质相互作用系统（如唾液腺、乳腺、羽毛、毛发和牙齿形态发生）的一个普遍特征。相比之下，我们已经证明，一种间充质可以被异源上皮诱导，大量合成与其来源器官不同的特定基因产物。第22 - 23阶段的禽肢芽上皮诱导17天胚胎小鼠牙齿间充质分化为软骨。肽分析（提取的胶原链纯化后用溴化氰裂解）表明，异源组织重组除了产生I型胶原[α(I)]₂α₂外，还产生了II型胶原[α(II)]₃（即软骨型）。完整的或重建的小鼠磨牙器官合成I型胶原和I型三聚体[α(I)]₃胶原。使用抗II型胶原抗体的免疫组织化学标准在异源组织重组体的间充质成分内的软骨样基质中鉴定出II型胶原。在体内或体外牙齿组织分化过程中从未描述过软骨，也未发现其与牙乳头间充质的病理学有关。这些结果支持了这样一种假说，即胚胎发育过程中的上皮-间充质相互作用可以选择性地诱导独特基因产物的从头合成。
