A Experimental Study Of The Initiation And Regeneration Of Condylar Cartilage In The Fetal Mouse Mandibule

The mandibular condylar cartilage, a kind of secondary cartilage, is an important part of mandibule for its growth. And it plays a significant role as the base in the physiological rebuilding and restoration from trauma of TMJ. Other tissue of the body heals by scar against trauma. But it is by regeneration of autologous tissue that rebuilds and restores bone and cartilage, which results from the fact that there is resemblance in molecular mechanism between the development of skelecton during the phase of embryo and physiological rebuilding and restoration from trauma of bone after birth. Current research focused mostly on the development and restoration by regeneration of cartilage of limb joints and epiphyseal growth cartilage, but it is still incipient to study the development and the mechanism of physiological rebuilding and restoration by regeneration of condylar cartilage. Therefore to study the molecule regulation mechanism of development and maturation of condylar cartilage in embryo, can not only discover the mechanism of its physiological rebuilding and restoration to set up the academic base for related treatment in clinic, but possiblely supply new treatment methods for trauma and destruction to articular cartilage.Histological and immunohistochemistry methods have been used to state the feature of development of the mandibular condylar cartilage, and molecule mechanism of its endochondral ossification. Studies show that the development mechanism of condylar cartilage differs from that of the long bone. In the early phase of endochondral ossification of the mandibular condylar cartilage, collagen I II and X are all expressed , the chondro-progenitor cells can differentiate directly into hypertrophic chondrocytes and condylar cartilage grow faster than the long bone. Inaddition, it can be seen form its histology and expression feature of collagen I and alkaline phosphatase(ALP) brings the evidence, that condylar cartilage may differentiate from differentiated mesenchymal cells in calcified pre-periosteal or osteoid-like tissue at the end of the mandibule.The mesenchymal cells of mancibular periosteal (MSMPs) are separated and cultured in vitro to study its bilogical feature. It is further confirmed by the experiment of muti-inducement that MSMPs can differentiate into osteocyte sand fibrocartilage cytes and it is osteo-chondro progenitor cells with the potential ability to evolve muti- differentiated. This added evidence to the view that condylar cartilage differentiated from osteo-chondro progenitor cells in the mesenchymal cells of mancibular periosteal.The mesenchymal cells of the cartilage-induced in mancibular periosteal is combined to the three-dimension gels scaffold of Chitosan -Polyelectrolyte Complex (CS-PEC) and transplanted into body as a whole to observe the formulation of fibrocartilage. It is showed, as a result, that osteo-chondro progenitor cells, derived from embryo, can act as the seed cell for regeneration of cartilage in TMJ and culture with CS-PEC as bracket can evolve into fibrocartilage in vivo.In conclusion, during the development of the mandibule, condylar cartilage derived from MSMPs at the end of the body mandibule. It can evolve into fibrocartilage cytes on appropriate condition and regenerate fibrocartilage provided with proper the three-dimension scaffold materials. Our research provides the initial frame for studying the development and physiological rebuilding of condylar cartilage, and regeneration of fibrocartilage. But it deserve further explore to learn features of its development and physiological rebuilding and features of the regeneration of fibrocartilage in histology, biochemistry and bio-mechanics.