Objective To study the healing ability of the central area tissue of flexor tendons after injury. Methods Tendons of flexor digitorum profundus of the long toes from 8 white Leghorn hens were harvested in zone II. Tissues were cut in 4 mm segments and divided into the experimental group(the central area tissue of flexor tendons) and the control group(the tendon segments without epitenon). There were 12 tendon segments cultured in each group. Specimens were obtained and examined under light microscope on the 9th, 18th and 27th days after culture, respectively. Another 4 tendons were used as normal control, and they were directly examined under light microscope. Results The number of tenocytes was significantly less in the control group than in the experimental group and the uncultured state (P＜0.01); the number of tenocytes was significantly higher in the experimental group than in the uncultured state (P＜0.01). The number of tenocytes of the experimental group were higher on the 9th day than on the 18th and 27th days after culture(P＜0.01). Conclusion The central area tissue of flexor tendons has favorable healing ability after injury.
OBJECTIVE: To establish the animal models of mandibular distraction osteogenesis in rabbits and study its osteogenetic mechanism. METHODS: The right mandibles just anterior to the first molars of 12 rabbits were performed osteotomies, and the mandibles were positioned with distractors. The left mandibles were control group without operation. After 1 week, the distractors were stretched 0.9 mm every day for 10 days progressively. One day, 2, 4, 8 weeks after distraction, the mandibles were studied with gross measurement, X-ray, and histological examination. RESULTS: The right mandible were lengthened 8.3 mm on average without bone nonunion and deformity healing. It was observed that the gaps between the distracted bone edges were first occupied by fibrous tissue. Two weeks after distraction, it was found that the gaps were bridged by callus in X-ray, the new bone and the normal bone could not be differentiated clearly after 8 weeks. In histological sections, there were collagen bundles in early distraction, then those collagen bundles were calcificated and become trabeculaes. No Cartilage was found during distraction. CONCLUSION: It suggests that the rabbit mandible can be lengthened by distraction osteogenesis, and the new bone is formed by intramembranous ossification.