Evidence for the role of the enamel knot as a control center in mammalian tooth cusp formation: non-dividing cells express growth stimulating Fgf-4 gene.
Evidence for the role of the enamel knot as a control center in mammalian tooth cusp formation: non-dividing cells express growth stimulating Fgf-4 gene.
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DOI：
10.1387/ijdb.7848830
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发表时间：
1994-09
期刊：
影响因子：
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通讯作者：
J. Jernvall;P. Kettunen;I. Karavanova;L. Martin;Irma Thesleff
中科院分区：
文献类型：
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作者：
J. Jernvall;P. Kettunen;I. Karavanova;L. Martin;Irma Thesleff
哺乳动物牙冠的主要形态特征是牙尖，但导致牙尖形成的发育机制尚不清楚。牙尖的形成开始于帽状期，伴随着釉质结的出现，釉质结是一簇不分裂的上皮细胞。在本研究中，釉结首次出现在胚胎小鼠磨牙的帽状期开始。在牙齿发育后期，在牙尖处观察到次级釉质结结构，其外观对应于个体牙尖形态的形成。比较胚胎小鼠磨牙细胞增殖的模式和成纤维细胞生长因子-4（Fgf-4）基因的表达，发现Fgf-4 mRNA的表达严格定位于釉结的非分裂细胞。然而，当FGF-4蛋白被引入到离体牙组织中时，它刺激牙上皮细胞和间充质细胞的增殖。基于这些结果，我们认为，牙釉质结可以控制牙齿形态发生，同时刺激牙尖生长（通过FGF-4合成）和直接折叠的尖瓣斜面（不增殖本身）。
The main morphological features of the mammalian tooth crown are cusps, but the developmental mechanisms that cause the formation of cusps are unknown. Tooth cusp formation commences at cap-stage with the appearance of the enamel knot, which is a cluster of non-dividing epithelial cells. In this study, enamel knot was first seen in embryonic mice molar teeth at the onset of cap-stage. Later in tooth development, secondary enamel knot structures were observed at the cusp tips and their appearance corresponded to the formation of individual cusp morphology. Comparisons of the pattern of cell proliferation in embryonic mouse molars and the expression of fibroblast growth factor-4 (Fgf-4) gene revealed that expression of Fgf-4 mRNA is strictly localized to the non-dividing cells of the enamel knot. However, when FGF-4 protein was introduced onto isolated dental tissues in vitro, it stimulated the proliferation of both dental epithelial and mesenchymal cells. Based on these results, we suggest that the enamel knot may control tooth morphogenesis by concurrently stimulating cusp growth (via FGF-4 synthesis) and by directing folding of cusp slopes (by not proliferating itself).