| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1996: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
In the present study, effects of various growth factors on the development of mouse tooth-germ in organ culture were investigated. Effects of EGF on the morphogenesis, cell proliferation and expression of extracellular matrix in embryonic day 15 mouse molar tooth-germs cultured in both serum-free and serum-containing media were studies histologically and immunohistochemically. After 6 days of culture in the serum-free medium with EGF,cusp formation and cervical loop growth were inhibited and an enamel organ showed a globular shape. In the serum-containing medium with EGF,cusp formation and cervical growth were irregular. After 9 days of culture in both media with EGF,some of dental papillar cells were observed outside the enamel organ. In BrdU incorporation study, cell proliferation of the inner enamel epithelium in both media with EGF was prolonged and appeared more diffusely than that in both media without EGF.The expression of extracellular matrix of the dental papilla in both media with EGF remained undifferentiated in comparison with that in both media without EGF.Effects of various growth factors, such as PDGF-AB,bFGF,aFGF,TGF-beta1 and HGF,on the morphogenesis and cell proliferation in tooth-germs cultured in the serum-free medium were also studied. In the addition of various growth factors, none of them affected the morphogenesis and cell proliferation of tooth-germ. In the addition of PDGF-AB or TGF-beta1 combination with EGF,however, tooth-germ showed an abnormal structure similar to that in the serum-containing medium with EGF.The results of the present studies suggested that exogenous EGF disturbed the well-ordered stimulus-arrest mechanism of dental cell proliferation and gave rise to inhibition and/or abnormality of tooth morphogenesis and that PDGF-AB or TGF-beta1 in serum modified the effect of EGF.
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