Spatiotemporal Expression Of CDC42 And PAR3 During Tooth Development In Mice

Objectives:To study the expressions of polarity related proteins CDC42 and PAR3 during tooth development in mice and discuss their possible roles during tooth development in mice.Methods:The whole mouse heads were obtained from embryonic day 13.5(E13.5),E14.5,E16.5 and E18.5 embryos and postnatal day 1(PN1)and PN5 mice.The tissues were fixed in paraformaldehyde,decalcified,dehydrated,embedded in paraffin,and sectioned.Histology during tooth development was observed by HE staining.The localizations and changes of CDC42 and PAR3 during tooth development were detected by immunohistochemistry staining.Results:HE staining showed that E13.5,E14.5,E16.5 and E18.5 are the bud stage,cap stage,early and late bell stage of tooth development,respectively;PN1 showed matured odontoblasts and ameloblasts;PN5showed completed tooth crown development.Immunohistochemistry staining showed that CDC42 was expressed in epithelium and mesenchyme during tooth development at E13.5,E14.5 and E16.5.CDC42 expression was reduced at E18.5,comparing with E13.5,E14.5and E16.5.At PN1 and PN5,CDC42 was expressed at the secreting sides of odontoblasts and ameloblasts.PAR3 was weakly expressed at E13.5and E14.5.At E16.5 and E18.5,PAR3 expressions were significantly enhanced.At PN1 and PN5,PAR3 expressions were decreased,comparedwith E18.5.Conclusion:CDC42 and PAR3 participate in mouse tooth development.During the early stage of tooth development,CDC42 and PAR3 may be involved in the proliferation and migration of the tooth mesenchymal cells.At E18.5 、 PN1 and PN5,CDC42 and PAR3 may be involved in the differentiation of odontoblasts and ameloblasts,especially in the establishment and maintenance of cell polarity.