Experimental Study Of Notch1 Signal Regulating The Development Of Tooth Germ And The Reparative Process In Injuried Tooth

Tooth germ Development is complicated, and regulated by various of intercellular signal. Tertiary dentin formation is in the same way, and many related genes are expressed. The evolutionarily conserved Notch-mediated intercellular signaling pathway plays an important role in cell differentiation, proliferation and apoptosis and is essential for proper embryonic development of many tissues and organs. Recent data suggested that Notch receptors and their membrane-bound ligands Delta and Serrate were involved in both patterning and cell fate determination during odontogenesis. Also, Notch pathway might have particular regulative function during the reparative process of pulp tissue after injury.Thus, Further study of Notch signal in odontogenesis and dentification may provide new strategy for vital pulp conservation inclinic. The main objective of this study is to observe the expression pattern of Notch 1 during the development of the tooth germ and the process of reparation of injuried tooth, and to observe the effect of Notch 1 on the formation of the dentine bridge. Contents of the investigation are as follows:1. Expression of Notch 1 in the developing process of the tooth germ of SD ratTooth expression of the Notch 1 in rat tooth germ was observed at E12, 14, 16, 17, 18, 19 and postnatal 1, 3, 5, 7, 9d using immunohistochemical staining technique. Results showed that the expression of the Notch 1 began at the middle bell stage. Weakly positive staining was observed in the mesenchymal cells in dental papilla and odontoblasts, and positive in the inner enamel cells from middle to late bell stage. At the beginning of dental hard tissues formation, Notch 1 was expressed in the stratum intermedium, transiently in odontoblasts. After tooth eruption and Notchl was negtive in odontoblasts and ameloblasts. Conclusion: Notchl might be involved in ameloblast differentiation during the development of the tooth germ.2. The expression of Notchl in rat dental pulp after injuryRat dental pulp injury experimental model was established and expression of Notchl was observed. The pulp of the first molar of the rats were exposed, and the samples of the dental pulp were obtained 2h, 12h, 24h,3d, 7d after injury. HE and immunohistochemiscal stained were performed. Results: Notchl was negatively stained in normal pulp tissues, while up-regulated in the injuried pulp. Notchl was weakly positive in the layer of odontoblasts and part of the dental...