Nishida K, Inoue H, Murakami T
Department of Orthopaedic Surgery, Okayama University Medical School, Japan.
Ann Rheum Dis. 1995 Dec;54(12):995-8. doi: 10.1136/ard.54.12.995.
To locate fibronectin ultrastructurally in the most superficial layer of normal articular cartilage of rabbits, in order to clarify its role in joint physiology.
Articular cartilage was obtained from the femoral condyle of seven normal adult rabbits and prepared by a method that included tannic acid fixation. Polyclonal antibodies against rabbit fibronectin were used in an immunohistochemical electron microscopic study, without any enzymic digestion but with a pre-embedding method for the transmission electron microscopy.
The cartilage surface was successfully preserved by tannic acid fixation. The most superficial layer in electron photomicrographs was approximately 200-300 nm thick, cell free, and appeared to have two parallel components: the more superficial lamina and the deeper lamina. Gold labelled fibronectin lined this layer in immunohistochemical electron photomicrographs.
Fibronectin covering the surface of the articular cartilage may have a role in joint lubrication and protection of the cartilage by binding with the collagenous matrix and hyaluronic acid in synovial fluid. Chondroitin sulphates may act as a charge barrier in close relationship with the collagen fibrils in the deeper lamina. Significant alteration in these functions may be one of the first causal steps leading to destruction of the articular cartilage.
在超微结构水平定位兔正常关节软骨最表层的纤连蛋白，以阐明其在关节生理学中的作用。
从7只正常成年兔的股骨髁获取关节软骨，采用包括鞣酸固定的方法进行制备。在免疫组织化学电子显微镜研究中使用抗兔纤连蛋白的多克隆抗体，不进行任何酶消化，采用透射电子显微镜的包埋前方法。
鞣酸固定成功保存了软骨表面。电子显微照片中的最表层约200 - 300纳米厚，无细胞，似乎有两个平行成分：较浅的薄片和较深的薄片。在免疫组织化学电子显微照片中，金标记的纤连蛋白排列在该层。
覆盖关节软骨表面的纤连蛋白可能通过与滑膜液中的胶原基质和透明质酸结合，在关节润滑和软骨保护中发挥作用。硫酸软骨素可能作为与较深薄片中的胶原纤维密切相关的电荷屏障。这些功能的显著改变可能是导致关节软骨破坏的首批因果步骤之一。
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