鼠颞颌关节中弹力纤维的电镜观察

为了进一步观察鼠颞颌关节各部位的有胶原纤维和弹力纤维，作者应用计算机图象分析系统和电镜来研究鼠颞颌关节中三种弹力纤维的分布与形态。结果表明：在关节各部位中的弹力纤维以微原纤维和前弹力纤维为主。关节盘表面的微原纤维排列方向与胶原纤维几乎成直角。在关节盘表层下方和关节其它部位的弹力纤维排列上未见方向性。弹力纤维在关节盘和关节囊中形成一个广泛的纤维网。     

兔髁突软骨组织学分层的实验研究

目的：探讨髁突软骨的组织分层及其功能。方法：成年日本大耳白兔6只,处死后通过HE染色、免疫组化、原位杂交和透射电镜等方法进行软骨细胞PCNA、FGFR3、Ⅱ型胶原和蛋白多糖聚合体基因表达及超微结构等研究。结果：FGFR3在增殖层的浅层细胞中阴性表达,增殖层深层细胞开始为阴、阳性染色相间,逐渐变为全阳性染色细胞。PCNA在增殖层浅层细胞为阴、阳性染色相间,深层细胞均为阳性表达。增殖层的浅层细胞有蛋白多糖聚合体mRNA表达,但不表达Ⅱ型胶原mRNA。增殖层的深层细胞均强表达Ⅱ型胶原和蛋白多糖聚合体mRNA。电镜下见增殖层的深层细胞具有幼稚细胞和软骨细胞的双重表型。结论：髁突关节软骨应分为纤维层、增殖层、过渡层、软骨层和钙化软骨层5层,过渡层细胞可能属于前软骨干细胞。     

Immunohistochemical study of matrilin-1 in arthritic articular cartilage of the mandibular condyle

BACKGROUND: The objective of this study was to investigate the expression of matrilin-1 in arthritic articular cartilage of the mandibular condyle by means of immunohistochemical methods. METHODS: Condylar cartilage specimens were obtained from temporomandibular joints (TMJs) of 12 patients with arthritis (osteoarthritis and internal derangement) (mean age 51.8 years; age range 28-71 years) and four patients with TMJ ankylosis (mean age 44.0 years; age range 16-64 years), diagnosed clinically and with imaging examinations. Paraffin sections were immunostained with anti-matrilin-1 antibodies. RESULTS: Matrilin-1 expression was detected in both patient groups with TMJ ankylosis and arthritis, and the level was remarkably higher in arthritic cartilage. The mean percentage of matrilin-1-producing cells to the total chondrocytes was significantly (P < 0.05) greater in the arthritic group (43.9 +/- 19.2%) than in subjects with TMJ ankylosis (28.0 +/- 8.7%). CONCLUSIONS: Articular chondrocytes in the TMJ condyle can express matrilin-1 and the expression is enhanced in arthritic cartilage, suggesting a presence of functional or adaptive remodeling in the condyle in response to degenerative changes in the TMJ structures.     

负荷改变对髁突软骨细胞合成蛋白多糖的影响

目的：研究负荷变化对髁突软骨细胞蛋白多糖合成的影响。方法：拔除成年家兔左下磨牙,分别于术后2周、1月和3月取双侧颞颌关节,进行阿辛兰和甲苯胺兰等组织化学染色和免疫组化染色。结果：酸性粘多糖和蛋白多糖术后量均降低,以非拔牙侧更显著,随着缺牙时间的延长这些变化而更显著。结论：异常负荷可导致软骨细胞蛋白多糖合成的减少及其构成的变化,从而使髁突纤维软骨的粘弹性降低。     

甲状旁腺激素相关蛋白mRNA在髁突软骨与生长板软骨发育早期的表达变化

目的研究甲状旁腺激素相关蛋白(parathyroid hormone-related protein,PTHrP)mRNA在髁突软骨与生长板软骨发育早期的表达变化,初步探讨PTHrP在软骨内成骨中的作用。方法选用胚胎SD大鼠的髁突软骨与生长板软骨作为研究对象,采用原位杂交染色法检测发育早期两种软骨内PTHrP mRNA表达,以图像分析仪进行图像分析。结果胎龄14～19 d,随着软骨发育的成熟,PTHrP mRNA在生长板软骨和髁突软骨中的表达越来越广泛并呈现一定的时空变化,但PTHrP mRNA在两种软骨中的表达部位存在一定的差异。在髁突软骨中,PTHrP mRNA在增殖层和前肥大层强表达;在生长板软骨中,其主要表达在软骨膜细胞和关节周围的软骨细胞,前肥大层中也有较强的表达,增殖层弱表达或不表达。结论 PTHrP mRNA在生长板软骨和髁突软骨中表达部位不同,但均呈现一定的时空变化,提示PTHrP对不同分化阶段的软骨细胞具有一定的调节作用。     

Ultrastructure of the articular cartilage of the mandibular condyle: aging and degeneration

To obtain more insight into the pathogenesis of osteoarthrosis of the temporomandibular joint, we examined the ultrastructure of articular cartilage of six healthy and sixteen osteoarthrotic human mandibular condyles. Ultrastructural changes due to aging and osteoarthrosis are described and compared with the findings of other ultrastructural studies of articular cartilage of synovial joints. Aging was accompanied by some slight degenerative signs. Osteoarthrotic hyaline cartilage and fibrocartilage showed a striking similarity. The only ultrastructural difference was the presence of elastic fibers in the latter. Therefore, both seem to have the same pathogenesis. Several current statements on the pathogenesis of osteoarthrosis are discussed.     

微RNA在下颌髁突软骨生长发育中作用的研究进展

微RNA(micro RNA,miRNA)是一类小的非编码单链RNA,通过与信使RNA结合发挥其生物学作用。研究显示miRNA可能在调节下颌髁突软骨的生长发育中起重要作用。本文就miRNA的产生及其作用机制,对下颌髁突软骨生长发育相关的miRNA研究进展进行综述,以期助于进一步研究下颌髁突软骨生长发育。     

Developmental characteristics of secondary cartilage in the mandibular condyle and sphenoid bone in mice

ObjectiveSecondary cartilage develops from osteochondral progenitor cells. Hypertrophic chondrocytes in secondary cartilage increase within a very short time and then ossify rapidly. In the present study, we investigated the sequential development process of osteochondral progenitor cells, and the morphology and size of hypertrophic chondrocytes in secondary cartilage.DesignICR mice at embryonic days (E) 14.5–17.5 were used. The mandibular condyle and the medial pterygoid process of the sphenoid bone were observed as secondary cartilage, and the cranial base and the lateral pterygoid process of the sphenoid bone, which is primary cartilage, were observed as a control. Thin sections were subjected to immunostaining and alkaline phosphatase (ALP) staining. Using a confocal laser microscope, 3D stereoscopic reconstruction of hypertrophic cells was performed. To evaluate the size of hypertrophic chondrocytes objectively, the cell size was measured in each cartilage.ResultsHypertrophic chondrocytes of secondary cartilage first expressed type X collagen (Col X) at E15.5. SRY-box 9 (Sox 9) and ALP were co-expressed in the fibroblastic/polymorphic tissue layer of secondary cartilage. This layer was very thick at E15.5, and then rapidly became thin. Hypertrophic cells in secondary cartilage were markedly smaller than those in primary cartilage.ConclusionsThe small hypertrophic cells present in secondary cartilage may have been a characteristic acquired in order for the cartilage to smoothly promote a marked increase in hypertrophic cells and rapid calcification.     

Expression of Notch1 and Math1 in mandibular condyle cartilage in neonatal mice

On the basis of the cellular morphological changes in the cartilaginous area, the mandibular condylar cartilage is histopathologically composed of four different cell layers--fibrous, proliferative, maturative, and hypertrophic. Reaction for Notch1 was present in the hypertrophic cells only. However, Math1 was locally distributed in the hypertrophic layer and partially in the proliferative layer. The expression patterns of Notch1 and Math1 were slightly different. These results suggest that the morphogenesis regulation factors of Notch1 and Math1 may play some role in mandibular condylar cartilage. Positive reactions to osteopontin, as a control, were detected in the cytoplasm of all layers, although they varied from published data.     

The surface structure of the human mandibular condyle in health and disease

Surface features of the human mandibular condyle have been studied by scanning and electron microscopy. Normal condyles possessed features similar to those in other diarthrodial joints but with certain differences. Two types of erosion and an exostosis were seen in diseased joints and the surface structure is described.     

Interleukin-1 beta affects cyclooxygenase-2 expression and cartilage metabolism in mandibular condyle

Extracellular matrix degradation in mandibular condylar cartilage is mediated by various cytokines in the temporomandibular joint (TMJ). Interleukin-1 beta (IL-1β) is detected in joint structures with pathologic status, and participates in catabolic action in the extracellular matrix. The purpose of this study was to investigate the effects of IL-1β on cyclooxygenase-2 (COX-2) expression and cartilage metabolism using cultured chondrocytes from mandibular condyle. Articular chondrocytes from the porcine mandibular condylar cartilage around the surface were cultured and treated with 0–10 ng/ml IL-1β or 0–1000 ng/ml prostaglandin (PGE₂) for 0–24 h. The mRNA levels of COX-2, MMP-1, -3, and -13 were evaluated by real-time PCR analysis. The protein levels of PGE₂ and MMPs were examined by ELISA and Western blot analysis, respectively. The expression levels of COX-2 and PGE₂ were enhanced by exogenous IL-1β in chondrocytes. The mRNA levels of MMP-1, -3, and -13 were up-regulated by PGE₂ treatment dose-dependently. It is shown that the expression of COX-2/PGE₂ was enhanced by IL-1β in articular chondrocytes from mandibular condyle, and that MMP-1, -3, and -13 were induced by PGE₂, suggesting that IL-1β-induced COX-2/PGE₂ play a crucial role in catabolic processes of mandibular condylar cartilage under inflammatory conditions.     

Histopathology of the mandibular condyle

Histological sections of mandibular condyles surgically removed from 40 female and 12 male patients who failed to respond to conservative management of temporomandibular joint related problems were examined. The proliferation, intermediate and cartilage zones were frequently either partly or completely absent in older subjects confirming previously held views of the functional significance of these zones. There was no obvious sex differences in the histological appearance of the condyle and evidence of inflammatory change was rarely seen.