The Expression Of Bone Morphogenetic Protein 4 In The Meckel's Cartilage And Its Implication In The Development Of Mandible

Objective: The purpose of this study was to observe the development of the mandible and the expression of bone morphogenetic protein 4(BMP4) in it in three-dimension continuously and to investigate both the implication of Meckel's cartilage in the mandible development and the role of BMP4 in the early stage of mandible development. Method:1 A series of three-dimensional (frontal,sagittal,horizontal) tissue section of the mandible of SD rat embryos between day 13 and 21,and at 1 day after birth were collected. HE stain was applied to observe the changes of Meckel's cartilage in the process of the mandible development. 2, The BMP4 mRNA expressions in the Meckel's cartilage were detected with in situ hybridization. Result: 1 The mandible development was evident on the lateral side of Meckel's cartilage at day 13, running along the Meckel's cartilage from posterior toward anterior, extending to its medial side, and finally covered the Meckel's cartilage. The anterior end of Meckel's cartilage ossified enchondrally and directly contributed to the growth of the mandible, but this condition couldn't be seen in the posterior part. 2, The BMP4 mRAN expression changed in all the stages of the mandible development. A higher BMP4 mRAN expression was observed in Meckel's cartilage cell at day 19 and a lower BMP4 mRAN expression was observed at day21. Conclusion: 1 Meckel's cartilage plays an important role in the mandible growth. 2 BMP4 may have a role as a mediator of the mesenchymal cell differentiation leading to the mandible formation.