上皮条件性敲除Bmp2和Bmp4对小鼠牙根长度的影响

Deletion of Bmp2 and Bmp4 from Epithelium Affected Tooth Root Development in Mice

目的:观察在上皮组织中条件性敲除Bmp2和Bmp4基因对小鼠牙根发育的影响,为深入研究牙根发育的分子机制提供前期基础。方法:利用Jackson Laboratory推荐的引物,对鼠尾组织进行聚合酶链式反应,鉴定小鼠基因型。取出小鼠下颌骨组织,经过相应处理后,进行石蜡包埋,用于HE染色。在牙根发育早期过程中比较Bmp2和Bmp4基因敲除组(double gene knockout,DcKO)与同源对照组(control,Con)小鼠的上皮根鞘(hertwig's epithelial root sheath,HERS)和根部成牙本质细胞的形态差异,在牙根发育完成后经小动物高清X线观察两组小鼠牙根状况。结果:出生后0 d,两组小鼠牙根尚未发育;出生后7 d,与对照组相比,实验组小鼠根部成牙本质细胞极化更差;出生后14 d,DcKO小鼠的HERS组织比Con组断裂程度低。牙根发育完成后,21 d和28 d的X线结果显示实验组小鼠的牙根比对照组短,根部髓腔比对照组小鼠大。结论:Bmp2和Bmp4基因参与小鼠牙根发育,Bmp2和Bmp4基因缺失可导致DcKO组小鼠的牙根变短。

Objective:To observe the effect of double deletion of Bmp2 and Bmp4 from epithelium on root development,which provide a preliminary basis for further study of molecular mechanism.Methods:The primers recommended by Jackson Laboratory were used to identify the genotype of the mice.The mandibles were prepared for HE staining.Morphological analyses of hertwig's epithelial root sheath(HERS)and root odontoblast cells were conducted in the Bmp2 and Bmp4 knockout mice and the control mice during root development.The roots from the control and DcKO mice were analyzed by plain X-ray radiography.Results:At postnatal 0 day(PN0),the roots did not develop yet.At PN7,the polarization of odontoblasts in DcKO mice was worse compared to that of the normal controls.At PN14,the terminal HERS had fragmented.In the DcKO group,the terminal HERS was more difficult to fragment.At PN21 and PN28,plain X-ray images indicated that the root length was significantly reduced and the root pulp cavity was increased in the DcKO mice.Conclusion:Bmp2 and Bmp4 genes are involved in the root development of mice.The deletion of Bmp2 and Bmp4 genes leads to shorter roots in the DcKO mice in contrast to control mice.