Methods: PCD was detected by TdT-mediated dUTP nick end labelling (TUNEL) in different stages of tooth development of SD rat. Results: The TUNEL showed that there was consistent PCD present in the bud stage, cap stage and bell stage.

• 方法：采用原位末端标记法（TUNEL法）及HE染色技术，对纯系SD大鼠牙胚发育不同阶段的程序性细胞死亡现象进行观察。 结果：在牙齿发育的蕾状期、帽状期、钟状期均有程序性细胞死亡现象。