Tooth development in a scincid lizard, Chalcides viridanus (Squamata), with particular attention to enamel formation
Tooth development in a scincid lizard, Chalcides viridanus (Squamata), with particular attention to enamel formation
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DOI：
10.1007/s00441-004-0950-2
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发表时间：
2005-01-01
影响因子：
3.6
通讯作者：
Sire, JY
中科院分区：
文献类型：
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作者：
Delgado, S;Davit-Béal, T;Sire, JY
牙齿发育的主要脊椎动物谱系的比较分析是必要的，以确定各种进化路线，导致目前的牙齿在生活的脊椎动物。利用光学显微镜、扫描电镜和透射电镜研究了绿脉小蜂科蜥蜴（Chalcides viridanus）牙齿的形态和牙齿发育的主要阶段，从晚期胚胎到6岁的实验室繁殖群体样本，以及从早期起始阶段到完全分化和附着，包括再吸收和釉质形成。In C.在绿齿象中，颌的所有牙齿具有相似的形态，但牙齿的形状、大小和方向在个体发育过程中发生变化，牙齿位置的数量不变。牙齿形态的变化，从一个简单的光滑的圆锥体在胚胎后期的两个尖和几个脊的典型成人方面通过连续的牙齿更换在每个位置。第一代牙齿是由口腔上皮和下颌下间充质之间的相互作用开始的。这些牙齿的牙板直接从口腔上皮的基底层分支。在前牙开始时，牙板从前牙的釉质器官展开。在牙板末端和骨支持表面附近的上皮细胞群增殖并分化成成釉器官，内（IDE）和外牙上皮被星状网分隔。IDE分化为成釉细胞，其产生釉质基质组分。在牙本质分化区，间充质细胞分化为牙乳头，形成成牙本质细胞，先在牙本质细胞表面沉积一层前牙本质基质存款。釉质基质的第一元素然后由成釉细胞合成。基质矿化开始于牙齿的上部区域（牙本质然后是釉质）。一旦釉质基质层完成，釉质就开始成熟。同时，牙基质朝向牙本质锥的基部沉积。釉质基质的成熟从顶部向底部进行;牙本质矿化从牙本质-釉质交界处向髓腔向心进行。牙齿附着是侧牙，牙齿替换发生在功能牙齿的牙本质锥被吸收的舌侧。吸收开始从一个更深的区域在成年人比在青少年。我们的研究结果使我们得出这样的结论，牙齿形态发生和分化，这蜥蜴是类似的哺乳动物牙齿。然而，Tomes的过程和釉质棱柱是缺席。
Comparative analysis of tooth development in the main vertebrate lineages is needed to determine the various evolutionary routes leading to current dentition in living vertebrates. We have used light, scanning and transmission electron microscopy to study tooth morphology and the main stages of tooth development in the scincid lizard, Chalcides viridanus, viz., from late embryos to 6-year-old specimens of a laboratory-bred colony, and from early initiation stages to complete differentiation and attachment, including resorption and enamel formation. In C. viridanus, all teeth of a jaw have a similar morphology but tooth shape, size and orientation change during ontogeny, with a constant number of tooth positions. Tooth morphology changes from a simple smooth cone in the late embryo to the typical adult aspect of two cusps and several ridges via successive tooth replacement at every position. First-generation teeth are initiated by interaction between the oral epithelium and subjacent mesenchyme. The dental lamina of these teeth directly branches from the basal layer of the oral epithelium. On replacement-tooth initiation, the dental lamina spreads from the enamel organ of the previous tooth. The epithelial cell population, at the dental lamina extremity and near the bone support surface, proliferates and differentiates into the enamel organ, the inner (IDE) and outer dental epithelium being separated by stellate reticulum. IDE differentiates into ameloblasts, which produce enamel matrix components. In the region facing differentiating IDE, mesenchymal cells differentiate into dental papilla and give rise to odontoblasts, which first deposit a layer of predentin matrix. The first elements of the enamel matrix are then synthesised by ameloblasts. Matrix mineralisation starts in the upper region of the tooth (dentin then enamel). Enamel maturation begins once the enamel matrix layer is complete. Concomitantly, dental matrices are deposited towards the base of the dentin cone. Maturation of the enamel matrix progresses from top to base; dentin mineralisation proceeds centripetally from the dentin-enamel junction towards the pulp cavity. Tooth attachment is pleurodont and tooth replacement occurs from the lingual side from which the dentin cone of the functional teeth is resorbed. Resorption starts from a deeper region in adults than in juveniles. Our results lead us to conclude that tooth morphogenesis and differentiation in this lizard are similar to those described for mammalian teeth. However, Tomes' processes and enamel prisms are absent.