[P1-3-08] Morphologic analysis of the regenerative process after amputation of lower jaw in adult newt
Keywords:再生、下顎骨・メッケル軟骨、歯
Objectives: Amphibian newts have been the subject of researches in the field of regeneration because of their ability to regenerate various tissues and organs. However, the dynamics of the regenerative process of newt jaws remain unclear. In this study, we investigated the morphologic changes to be seen in the regenerative process of newt mandibular tissues. Materials & Methods: The adult newts (Cynops Pyrrhogaster) , which are Japanese local variety, were used in this study. Under general anesthesia, the newt mandibles were amputated in the anterior half. We analyzed the morphologic dynamics in the regenerating lower jaws after amputation during 0-60 weeks according to X-ray microtomography (microCT) with three-dimensional reconstruction and measuring software (TRI/3D-BON-FCS64) and histological approaches. Results: The regenerative changes of jaws occurred in all newts amputated. The wound was covered by the epithelium after 1 week. Around 3 weeks after the amputation, the wound was almost completely healed. A blastema was formed at the amputation site of the mandible, and various tissues and organs began to regenerate according to the various cell differentiation of blastema cells. The mandible began to elongate toward the chin, and first, angiogenesis occurred, followed by the regeneration of various tissues such as lymphatic vessels, nerve axons, skeletal muscles, tongue, and salivary glands. In the skeletal system, the regeneration of dentary bone began around 8 weeks after amputation along with the elongation of Meckel's cartilage, and progressed to the vicinity of the midline after 16 weeks. Many conical regenerated teeth with enamel and dentin were arranged on the newly formed dentary bone. Around 32 weeks after amputation, the addition of bone to the lingual side of the dentary bone resulted in progressive mandibular bone formation. Around 60 weeks, the mandibular bone had almost recovered to its thickness before amputation. Conclusion: These results indicate that adult newts have a vigorous regenerative ability and that the excised mandibular tissues were reconstructed to its original tissue structures. Supported by JSPS KAKENHI Grant number 18H04061. Non-member co-authors: Sayaka Kawamoto, Div Gen Dent, Nippon Dent Univ Hosp, Tatsuyuki Ishii and Kazuo Kishi, Dept Plast Reconstr Surg, Keio Univ Sch Med, Chikafumi Chiba, Dept Regen Physiol, Fac Life Environ Sci, Tsukuba Univ.