RESUMO
Objective:To explore the function of the bridging epithelium between maxillary process and nasal process in the devel-opment of lip and palate.Methods:The fertilized white leghorn chick eggs incubated to the appropriate Hamburger and Hamilton(H-H)stages were examined by tissue histologic studies,scanning electron microscopy observation,BrdU assay and TUNEL assay re-spectively.Results:At H-H stage 24,the epithelia between maxillary,lateral nasal and globular process were juxtaposed.At H-H stage 26-27,string-like filopodia appeared and the bridging epithelium formed,then in the bridging epithelium cell proliferation was decreased and the apoptotic cells appeared.At H-H stage 28,the apoptosis of the bridging epithelium cells increased,the full fusion of the processes was completed.Conclusion:The occurrence of bridging epithelium between maxillary process and nasal process plays an important role in the development of lip and palate.