RESUMEN
Joints enable the relative movement between the connected bones. The shape of the joint is important for the joint movements since they facilitate and smooth the relative displacement of the joint's parts. The process of how the joints obtain their final shape is yet not well understood. Former models have been developed in order to understand the joint morphogenesis leaning only on the mechanical environment; however, the obtained final anatomical shape does not match entirely with a realistic geometry. In this study, a computational model was developed with the aim of explaining how the morphogenesis of joints and shaping of ossification structures are achieved. For this model, both the mechanical and biochemical environments were considered. It was assumed that cartilage growth was controlled by cyclic hydrostatic stress and inhibited by octahedral shear stress. In addition, molecules such as PTHrP and Wnt promote chondrocyte proliferation and therefore cartilage growth. Moreover, the appearance of the primary and secondary ossification centers was also modeled, for which the osteogenic index and PTHrP-Ihh concentrations were taken into account. The obtained results from this model show a coherent final shape of an interphalangeal joint, which suggest that the mechanical and biochemical environments are crucial for the joint morphogenesis process.
Asunto(s)
Simulación por Computador , Articulaciones/crecimiento & desarrollo , Morfogénesis , Membrana Sinovial/crecimiento & desarrollo , Algoritmos , Humanos , Presión Hidrostática , Articulaciones/anatomía & histología , Osteogénesis , Estrés Mecánico , Membrana Sinovial/anatomía & histologíaRESUMEN
The aim of this study was to analyze the rat temporomandibular joint (TMJ) synovial membrane at different ages using light, scanning, and transmission electron microscopy. Under light microscopic analysis, the TMJ structures were observed such as condyle, capsule, disk, the synovial membrane collagen type, and cells distribution. In the scanning electron microscopy, the synovial membrane surface exhibited a smooth aspect in young animals and there was an increase with ageing in the number of folds. The transmission electron microscopic analysis showed more synoviocytes in the synovial layer in the young group and still a great number of vesicles and cisterns dilation of rough endoplasmic reticulum in the aged group. In the three groups, a dense layer of collagen fibers in the synovial layer and cytoplasmic extensions were clearly seen. It was possible to conclude that synovial membrane structures in aged group showed alterations contributing to the decrease in joint lubrication and in the sliding between disk and joint surfaces. These characteristic will reflect in biomechanics of chewing, and may cause the TMJ disorders, currently observed in clinical processes.
Asunto(s)
Membrana Sinovial/anatomía & histología , Membrana Sinovial/ultraestructura , Articulación Temporomandibular/anatomía & histología , Articulación Temporomandibular/ultraestructura , Envejecimiento , Animales , Microscopía , Ratas WistarRESUMEN
Foram dissecados em sala de autópsia 100 joelhos de 50 cadáveres frescos (näo formolizados), adultos, do sexo masculino, utilizando incisao parapatelar lateral, com secçäo parcial dos tendöes quadricipital e patelar; observou-se presença ou näo de pregas sinoviais mediais, que foram classificadas em quatro diferentes tipos morfológicos. Constataram-se lesöes associadas em meniscos, ligamentos, cartilagem e sinovial. Obteve-se, com essas observaçöes, a incidência da prega medial e sua correlaçäo com outras alteraçöes intra-articulares e idade, concluindo näo haver qualquer relaçäo entre incidência de prega medial e idade. Também näo ficou demonstrada qualquer correlaçäo com outras alteraçöes, a näo ser uma erosäo longitudinal na cartilagem articular da faceta medial da patela, em apenas um caso.