PCNA AND Retinoic Acid On Expression Of Yunnan Blue - Tailed Newt In The Regeneration Of Mandible

[Objectives]Use the unique resources of our province-Yunnan blue tail salamander (Cynops cynaurus) as the research object to explore the method of establishing the model for the mandibular regeneration.Meanwhile,to investigate the characteristic expression of proliferating cell nuclear antigen(PCNA) and retinoic acid(RA) during mandibular regeneration.[Method]Partial mandibular amputations were performed on twenty-eight wild type adult Cynops cynaurus under general anesthesia.The samples were obtained and observed morphologically and histologically at different intervals of 3 days and 1,2,3, 5,7,12 weeks postoperatively.[Results]All experimental animals survived and jaws regenerated without any complications.The regeneration process in general as follows:1.wound healing;2. dedifferentiation of tissue;3.formation of regeneration blastema;4.formation of regenerate jaws.Immunohistochemical staining showed that the basal epidermal cells were PCNA positive during the regeneration process of the mandible.Different time points of the regeneration process,the regions of PCNA positive expression are differences.The expression of RARαlocated mainly in the epidermis and cartilage tissues,which seems associated with cell division and differentiation.Blastemal cells proliferated and differentiated three weeks after amputation while chondrogenesis, especially the regeneration of stump cartilage happened five weeks later.The stronger expressions of PCNA and RARαwere among 3,5,7 weeks postoperatively and the positive climax was at the 5th week.Twelve weeks later,the regenerative process of mandible appeared relatively slow and stable when the shape and function of mandible restored and RARαexpression declined rapidly.[Conclusion](1) Cynops cynaurus has the capacity of regeneration a new mandible. (2) PCNA and RARαexpressed positively during regenerative process.(3) Retinoic acid(RA) played an important role in the proliferation and differentiation of blastemal cells into chondrocytes.(4) A biological model has been created successfully on adult Cynops cynaurusr for studying mandibula regeneration.