Vaahtokari A, Aberg T, Jernvall J, Keränen S, Thesleff I
Institute of Dentistry, University of Helsinki, Finland.
Mech Dev. 1996 Jan;54(1):39-43. doi: 10.1016/0925-4773(95)00459-9.
Mammalian tooth forms are produced during development by folding of the enamel epithelium but the molecular mechanisms involved in the formation and patterning of tooth cusps are not understood. We now report that several key signaling molecules found in well-known vertebrate signaling tissues such as the node, the notochord, the apical ectodermal ridge, and the zone of polarizing activity in the limb bud are specifically expressed in cells of the enamel knot, which is a transient cluster of dental epithelial cells. By comparing three-dimensional reconstructions of serial sections following in situ hybridization we localized Sonic hedgehog, Bone morphogenetic proteins-2, -4 and -7, as well as Fibroblast growth factor-4 in nested domains within the enamel knot. We suggest that the enamel knot acts as a signaling or organizing center, which provides positional information for tooth morphogenesis and regulates the growth of tooth cusps.
哺乳动物的牙齿形态是在发育过程中由釉质上皮折叠形成的，但牙齿尖部形成和模式化所涉及的分子机制尚不清楚。我们现在报告，在一些著名的脊椎动物信号组织中发现的几种关键信号分子，如原结、脊索、顶端外胚层嵴和肢芽中的极化活性区，在釉结细胞中特异性表达，釉结是牙上皮细胞的一个短暂聚集区。通过比较原位杂交后连续切片的三维重建，我们将音猬因子、骨形态发生蛋白-2、-4和-7以及成纤维细胞生长因子-4定位在釉结内的嵌套区域。我们认为，釉结作为一个信号或组织中心，为牙齿形态发生提供位置信息并调节牙尖的生长。
