FIGURE 1 Schematic of tendon structure and composition.
From the following article:
Tendinopathy—from basic science to treatment
Graham Riley
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Figure 1. Schematic of tendon structure and composition.
The tendon midsubstance (A) is a dense, fibrous connective tissue of crimped fiber bundles, mostly aligned with the long axis of the tendon. The matrix consists predominantly of type I collagen, with lesser amounts of 'minor' collagens, proteoglycans and other glycoproteins. The tendon-bone insertion (enthesis) (B) shows more rounded cells with an Indian-file appearance and a gradual transition from tendon (T) to fibrocartilage (F) to calcified fibrocartilage (C) to mineralized bone (M). The matrix composition of the enthesis is similar to the tendon midsubstance but also contains additional 'minor' collagens and increased quantities of the proteoglycans aggrecan and biglycan. Photomicrographs (A) and (B) are H&E-stained sections of tendon midsubstance and insertion, respectively. Abbreviations: COMP, cartilage oligomeric matrix protein; dw, dry weight; H&E, hematoxylin and eosin.