Vidal Benedicto de Campos, Dos Anjos Eli Heber M, Mello Maria Luiza S
Department of Structural and Functional Biology, Institute of Biology, University of Campinas (Unicamp), 13083-862, Campinas, SP, Brazil.
Cell Tissue Res. 2015 Oct;362(1):177-85. doi: 10.1007/s00441-015-2173-0. Epub 2015 Apr 14.
Entheses are specialized biological structures that functionally anchor tendons to bones. The complexity, mechanical characteristics and properties of the entheses, particularly those related to exercise, mechanical load and pathologies, have been extensively analyzed; however, the macromolecular organization of the enthesis fibers, as assessed by polarization microscopy, has not yet been investigated. Morphological and optical anisotropy characteristics, such as birefringence, linear dichroism (LD) and differential interference contrast (DIC-PLM) properties, are thus analyzed in this study of a healthy adult mouse calcaneal tendon-bone enthesis. The molecular and supramolecular order of collagen and GAGs was determined for the collagen bundles of this enthesis. Based on a birefringence plot pattern as well as on metachromasy and linear dichroism after toluidine blue staining at pH 4.0, a similarity between the calcaneal tendon-bone enthesis and cartilage during ossification may be assumed. This similarity is assumed to favor the adequacy of this enthesis to support a compressive load. Considering that the collagen-proteoglycan complexes and the enthesis fibers themselves have a chiral nature, these structures could be acting via reciprocal signaling with the cellular environment of the enthesis.
附着点是将肌腱功能性地附着于骨骼的特殊生物结构。附着点的复杂性、力学特性和属性，尤其是与运动、机械负荷和病理相关的特性，已经得到了广泛分析；然而，通过偏振显微镜评估的附着点纤维的大分子组织尚未得到研究。因此，在这项对健康成年小鼠跟腱-骨附着点的研究中，分析了形态学和光学各向异性特征，如双折射、线性二色性（LD）和微分干涉对比（DIC-PLM）特性。确定了该附着点胶原束中胶原蛋白和糖胺聚糖的分子和超分子排列顺序。基于双折射图谱模式以及在pH 4.0条件下甲苯胺蓝染色后的异染性和线性二色性，可以假设跟腱-骨附着点与骨化过程中的软骨之间存在相似性。这种相似性被认为有利于该附着点支撑压缩负荷的适宜性。考虑到胶原-蛋白聚糖复合物和附着点纤维本身具有手性性质，这些结构可能通过与附着点细胞环境的相互信号传导发挥作用。
