Comparison Of FGF Expression Patterns And Their Functional Analysis In Human And Mouse Tooth Germ

Tooth development involved highly regulated reciprocal signaling interactions between the epithelium and mesenchyme, followed by lamina stage, bud stage, cap stage, bell stage, maturation stage. The current understanding of tooth development mostly came from mice, which was a model for researching tooth development. But few research was directly to human tooth development. What’s more there were some large different from either physiological development time or mechanics of development between human and mouse tooth’s developmet. Therefore it was very necessary to research human tooth development directly, which could provide data and theoretical basis that supported for the regeneration of human tooth.FGFs played an important role in reguating a variety of cells and tissues’proliferation, differentiation, survival and motility. Many studies, which using mice as tooth development animal model, showed that FGFs played an important role in the regulation of tooth development. Almost all Fgfs and Fgfrs participated in the regulation of tooth development.The main contents and conclusions of this study were as follows:Firstly, the research of FGF expression patterns in human tooth germ. Using hybridization in situ to confirm the expression patterns of FGF1, FGF2, FGF3, FGF4, FGFS, FGF7, FGF8, FGF9, FGF10, FGF15/19, FGF18, FGF20and FGF23in human tooth germ. The study showed there was a big difference in expression patterns of FGF4, FGF7, FGF8, FGF9, FGF10, FGF15/19and FGF18between human and mouse tooth germ. During mouse tooth development, the expression of Fgf4was limited in enamel knot of cap stage and bell stage. But in human tooth development, it expressed in both cap stage and bell stage’s epithelium and mesenchyme. Fgf7was hardly expressed during mouse tooth development. But at cap stage and bell stage of human tooth germ, FGF7was highly expressed in both epithelium and mesenchyme. In mouse tooth development, the expression of Fgf8started at epithelium of tooth initiation stage and then was no longer expressed after bud stage. But in human tooth germ, FGF8is highly expressed in both cap stage and bell stage’s epithelium and mesenchyme. In mouse tooth germ, Fgf9was little expressed in epithelium and enamel knot. But in human tooth germ, FGF9were strongly expressed in the cap stage and bell stage’s epithelium and mesenchyme. In mouse tooth development, the expression of Fgf10began at epithelium of tooth initiation stage and then were in mesenchyme in the subsequent stages. But in the early development of human tooth, FGF10was almost no expression. In mouse tooth development, the expression of Fgfl5/19started at epithelium of tooth initiation stage and then was no expressed at bud stage. At cap stage, Fgf15/19was expressed in enamel knot. At bell stage the expression of Fgf15/19was transferred to mesenchyme beneath secondary enamel knots. In human tooth germ, FGF15/19was highly expressed in both cap stage and bell stage’s epithelium and mesenchyme. In mouse tooth germ, the expression of Fgf18was limited to mesenchyme of limana stage, bud stage and cap stage. But in human tooth germ, FGF18is highly expressed in both cap stage and bell stage’s epithelium and mesenchyme. Secondly, researching FGFs function of tooth development in mammals. Using ectopic expression techniques, ectopic express Fgf7, Fgf9, Fgfl7and Fgf18in mouse tooth germ.The restruction experiment showed Fgfl8could delay mouse tooth development, suggested that Fgf18was one of the key factors in regulating the rate of tooth development.