| The rumor-necrosis-factor-family molecule osteoprotegerin ligand(OPGL; also known as TRANCE,RANKL and ODF)has been lately identified as a potential osteoclast differentiation factor that distributes in bone,blood and immune system.During bone remodeling,it can induce osteoclasts fusion, differentiation,maturation and so on.OPGL plays diverse roles in different tissues. The receptor activator of nuclear factor K B(RANK)was identified as a TNF super family member.It is the receptor of OPGL on osteoclast precursor cells.OPGL binds specifically to RANK and transfers the potential osteoclastogenic signals such as cell differentiation into osteoclast precursor cells to stimulate the latter fusing and activating.Osteoprotegerin(OPG) is also a new member of TNF receptor family which plays a key role in the physiological regulation of osteoclastic bone resorption.The protein,which is produced by osteoblasts and marrow stromal cells,acts by binding to its natural ligand OPGL and this binding prevents OPGL from activating its cognate receptor RANK,which is the osteoclast receptor vital for osteoclast differentiation,activation and survival. Overexpression of OPG in transgenic mice leads to profound osteopetrosis secondary to a near total lack of osteoclasts.OPGL-RANK-OPG comprises a keycytokone system that governs osteoclast develoment and regulates bone morphogenesis and resorption.At present,the study of the three cytokines focuses on bone remodeling.The replacement of primary and permanent teeth is an important part that belongs to the growth and development of animals' teeth and maxillofacial region.A lot of changes have taken place in the correlated tissues including the primary teeth,alveolar bone,periodontal ligament and the successional permanent teeth germs during this procedure.Until now,there is not any report concerning about the roles of the three cytokines in the replacement of the primary and permanent teeth.So in our study,we observed OPGL and its' receptor RANK expressions in deciduous teeth roots,periodontal ligament, alveolar bone and permanent teeth germs under three states of the dogs' teeth (primary dentition roots stability,primary dentition roots resorption,permanent dentition)by immunohistochemical technique,in situ hybridization method and cell culture.The main content and results of our researches are below:Parti OPGL expression during the replacement of dogs' primary and permanent teethThere were two experiments in part 1.Immunohistochemical technique and in situ hybridization method were used in this study to observe the OPGL expression under three states of the dogs' teeth: primary dentition roots stability,primary dentition roots resorption, permanent dentition.1.1 dogs' primary dentition roots stability stage:The deciduous teeth roots were not absorbed biologically.The permanent teeth germs were developing and dentin and enamel matrix started to form.In the immunohistochemical experiment, OPGL positive signals were seen in the multinucleated osteoclasts localized in the absorbed lacunae of the alveolar bone near the germs,as well as ameloblasts, odontoblasts of the permanent teeth germs. We also detected that enamal matrix of the permanent teeth germs dyed brown in the experimentln the in situ hybridization experiment, we saw that OPGL-positive cells were identified as osteoblasts in the alveolar bone and odontoblasts of the germs.These resultsindicated that osteoblasts and odontoblasts expressed OPGL and OPGL involved in the development of dogs' permanent teeth germs during the stages of the primary dentition roots stability.1.2 dogs' primary dentition roots resorption stage :Dogs' deciduous teeth roots were undergoing absorbed biologically and there were a lot of absorbed lacunae on the roots.Dentin and enamel of the permanent teeth germs went on forming and calcifying.Ameloblasts appeared to tall posts and the nuclears were away from the membranes.In the immunohistochemical experiment,the OPGL-positive signals were observed on osteoclasts in...
|
PDF Full Text Request