| Stomotology department. Zhejiang UniversityGraduate student: Feng Jiany ingAdvisor: Prof. Gu ZhiyuanPart One The genes expressions of chondrocyte extracelluar matrix in the development of rabbit temporomandibular jointCollagen II and aggrecan are the important components of chondrocyte extracelluar matrix. Excreted by chondrocyte, they reflect the functional state of chondrocyte and the environment of extracelluar matrix. In order to study the expressions of these genes during the rabbit temporomandibular joint development, we prepared the rabbit temporomandibular joints including the ages of 5, 10, 15, 30, 45, 60, 120 days. cRNA probes of rabbit collagen II and aggrecan were synthesized to detect the genes expressions by in situ hybridization.The results showed that the collagen fibers in temporomandibular joint disc emerged and arranged in order following the growth of rabbits. In 30 days immature chondrocytes appeared first in the posterior band of discs. Aggrecan and collagen mRNA could be detected one after another there. The genes expressions increasedgradually and the staining areas expanded to the anterior, medial and posterior bands^ of discs. Until 120 days the discs grew into mature fibrocartilage. Collagen II andaggrecan mRNA slightly co expressed in the hypertrophic zone of condyle cartilage in 5 days. With the development of articular, the proliferation cells differentiated into hypertrophic cells, and the cartilage thickened. After 30 days of birth, condyle cartilage differentiated into 4 zones. Collagen II and aggrecan co expressed in theproliferative zone, hypertrophic zone and calcificative zone, while no hybridizing signal showed in the fibrial zone. Thereafter the two genes expressed stronger gradually, especially in the condyle peak, which suffered the load of mastication, and reduced following the posterior slope of condyle.In our experiment, collagen II and aggrecan did not present synchronously in disc. Co expression of both genes indicated the maturation of chondrocytes. Articular load could accelerate the differentiation of chondrocytes in disc and condyle; enhance the matrix gene expression as well. The raise of collagen II and aggrecan genes expressions contributed to the articular cartilage resisting the increasing load.Part Two The genes and proteins expressions of chondrocyte extracelluar matrix in rabbit TMJ following disc displacementThe temporomandibular joint remodels after anterior disc displacement. It represents not only the emergence of chondrocyte-like cells and compact fibers in the disc posterior attachment, but also the changes of condyle morphology and structure. However, whether these neonatal chondrocyte-like cells in posterior attachment do have the characteristic of chondrocytes? The objective of our experiment is to identify these cell, and to discuss how chondrocyte function and matrix synthesize interfere with the course of temporomandibular joint disorders.40 adult Japanese white rabbits were studied. The right joints of 28 among 40 rabbits were subjected to surgical operation of disc displacement without opening joint bursas. Four of them were killed respectively in 4 days, 1, 2, 4, 6, 8 and 12 weeks post-operation. The control group was composed with 10 rabbits, which were performed sham operation without moving the discs, and another 2 rabbits without operation. We studied these TMJs by histochemistry, in situ hybridization, immunohistology and Alcian blue staining.In control group, collagen II and aggrecan mRNA expressed in articulardisc ,but no collagen II staining signal could be detected in disc posterior attachment. After operation, the discs showed different degrees of destroy firstly. 4 weeks later, collagen in posterior attachment became dense. Chondrocyte-like cells were found not only in the discs, but also in disc posterior attachments. These cells expressed collagen II, aggrecan mRNA and proteins, which was confirmed by in situ hybridization and immunohistology. In control group, the...
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