Structural, morphological and functional analysis of superficial digital flexor chicken tendons / Analise estrutural, morfologica e funcional do tendão flexor digital superficial de frangos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The structure-function relationship has been shown in several works regarding collagenous tissues, such as tendon. It is known that different loads can alter composition, molecular organization and morphological characteristics. Tendons present viscoelastic behavior and this characteristic is studied by biomechanical analyses and is directly related to tissue component organization. The aim of this work was to describe the importance of noncollagenous components on tendon viscoelasticity by analyzing changes in the organization and arrangement of extracellular matrix constituents and, consequently, changes in tendon morphology after mechanical tests. Chicken tendons were chosen due to their organization and composition; besides presenting a good length for mechanical tests. Superficial digital flexor chicken tendons were dissected and distributed into 3 groups: group I, non-treated; group II, tendons treated with testicular hyaluronidase; and group III, tendons treated with papain. Then, dimensional parameters, such as weight, width, thickness and cross-sectional area, were measured. The tendons were preserved in physiological solution until use in the mechanical tests. During the mechanical tests, they were tensioned and immediately afterwards were fixed and processed for morphological and histochemical analyses. The mechanical test results of groups II and III showed decreased ultimate tensile strength, elastic energy and elasticity modulus values, when compared with group I. In contrast, the ultimate strain values were highest for group II, indicating that after enzymatic treatment the tendons lost their capacity to resist tensile forces. Groups II and III presented different deformations in comparison with group I. Histochemical analysis confirmed the removal of the noncollagenous components in groups II and III. Spectral absorption curves were obtained for the non-stretched and group I tendon sections (non-treated to enzyme, but stretched) stained with toluidine blue and Ponceau SS. In group I sections stained with toluidine blue, two absorption peaks was observed, while in the non-stretched sections only one absorption peak was observed. Negative groups of GAGs available in non-stretched tendon sections most likely became unavailable in stretched tendons sections. Sections stained with Ponceau SS showed one absorption peak and group I sections showed the highest absorbancy values. Deformation of tendinous materials could involve a number of mechanisms, like collagen uncrimping. Collagen uncrimping could be involved in the unavailable of negative GAG groups and the highest absorbancy values in group I sections stained with Ponceau SS. In conclusion, tendon component constituents are dynamic, highly organized and oriented structures capable of rearranging during stretching. Moreover, the noncollagenous components are fundamental to tendon functions

ASSUNTO(S)

colageno biomecanica biomechanics proteoglycans proteoglicanos glicosaminoglicanos collagen glycosaminoglycans

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