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译者：武俊杰

对于牙根部上皮细胞转归的体外调节

通常认为，鼠类的磨牙不具备持续生长能力。我们提出假说，即鼠类磨牙具有维持上皮干细胞龛的内在潜能，并通过体外实验来证明此假说。经过体外器官培养后，虽然牙胚变得扁平，但是仍然发育出牙冠和牙根。组织学观察显示，牙根表面由三个不同区域组成，这些不同的区域对牙上皮产生影响。前方和后方部位具有连续的成釉细胞层，具备切牙颈环的形态和分子特征。与滤膜接触的上皮类似上皮根鞘结构。而暴露于空气中的磨牙顶部则出现上皮缺失。由此，我们得出结论，牙根部上皮细胞转归受到外部培养条件的影响，并且磨牙也具备内在的持续生长能力。

/digest/te/2007-11-11/24002.html
译者：霍娜

牙根中上皮细胞命运的体外调节

正常情况下小鼠磨牙不能持续生长。我们认为小鼠磨牙具有维持上皮干细胞龛的内在潜能并利用体外实验验证这一观点。在体外培养中磨牙牙胚形状扁平，具有矿化的牙冠和牙根。组织学上牙根表面由3种结构不同的区域分别影响着牙源性上皮的命运。根面前方和后方结构在形态和分子特性上都保持着持续生长的切牙颈环特征，可见持续存在的成釉细胞。而与支持滤膜接触的上皮类似于上皮根鞘结构。暴露于空气中的牙胚顶部则缺乏上皮结构。由此可见，牙源性上皮的命运受到培养环境等外部条件的调节，且磨牙具有持续生长的固有潜力。

J Dent Res. 2007 Nov;86(11):1063-7. Related Articles, Links
    Click here to read
    Modulation of Epithelial Cell Fate of the Root in vitro.
    Tummers M, Yamashiro T, Thesleff I.
    Developmental Biology Program, Institute of Biotechnology, Viikki Biocenter, PO Box 56, FIN-00014, Helsinki, Finland; and.

    Mouse molars are normally not capable of continuous growth. We hypothesized that the mouse molar has intrinsic potential to maintain the epithelial stem cell niche and assessed this potential by growth in vitro. Although the tooth germs flattened considerably, they developed a mineralized crown and a root. However, histologically, the root surface was composed of 3 structurally different regions affecting the fate of the dental epithelium. The anterior and posterior aspects maintained the morphological and molecular characteristics of the cervical loop of a continuously growing incisor, with a continuous layer of ameloblasts. The epithelium making contact with the supporting filter resembled Hertwig's epithelial root sheath. The top of the cultured molar exposed to air lacked epithelium altogether. We conclude that the fate of the epithelium is regulated by external cues influenced by culture conditions, and that the molar has the intrinsic capacity to grow continuously.