Diekwisch T G, Berman B J, Gentner S, Slavkin H C
Center for Craniofacial Molecular Biology, School of Dentistry, University of Southern California, Los Angeles, CA 90033.
Cell Tissue Res. 1995 Jan;279(1):149-67. doi: 10.1007/BF00300701.
During epithelial-mesenchymal interactions associated with mammalian tooth development, epithelially-derived and mesenchymally-derived extracellular matrix molecules form a discrete dentine-enamel junction. The developmental and molecular processes required to form this junction are not known. To address this problem we designed studies to test the hypothesis that ectodermally-derived epithelial cells synthesize and secrete enamel proteins which function to nucleate and regulate the growth of enamel calcium phosphate crystals. Initial enamel crystals were detected separate from the adjacent dentine. Electron-microprobe analyses revealed that early enamel crystals were octacalciumphosphate or tricalciumphosphate rather than hydroxyapatite. Thereafter, enamel crystals became confluent with the adjacent, albeit significantly smaller hydroxyapatite crystals associated with mineralized dentine. Therefore, we interpret our data to indicate that de novo enamel crystal nucleation and growth are independent from the mineralization processes characterized for dentine. We further argue that gene expression of enamel protein appears to have a constitutive function during early enamel formation and that supramolecular aggregates of amelogenin and enamelin provide the microenvironment for the nucleation and crystal growth of the initial enamel matrix.
在与哺乳动物牙齿发育相关的上皮-间充质相互作用过程中，上皮来源和间充质来源的细胞外基质分子形成一个离散的牙本质-釉质交界。形成这个交界所需的发育和分子过程尚不清楚。为了解决这个问题，我们设计了研究来检验以下假设：外胚层来源的上皮细胞合成并分泌釉质蛋白，这些蛋白起到使釉质磷酸钙晶体成核并调节其生长的作用。最初的釉质晶体与相邻的牙本质分开被检测到。电子微探针分析表明，早期釉质晶体是磷酸八钙或磷酸三钙，而不是羟基磷灰石。此后，釉质晶体与相邻的、虽然明显较小但与矿化牙本质相关的羟基磷灰石晶体融合。因此，我们对数据的解释表明，釉质晶体的从头成核和生长独立于牙本质的矿化过程。我们进一步认为，釉质蛋白的基因表达在早期釉质形成过程中似乎具有组成性功能，并且釉原蛋白和釉蛋白的超分子聚集体为初始釉质基质的成核和晶体生长提供了微环境。
