Fig. 1.

The tendon’s hierarchical structure begins at the molecular level with tropocollagen¹. Approximately five tropocollagen molecules form a microfibril, which then aggregate to create a subfibril¹. Several subfibrils form a single fibril. Multiple fibrils form a tendon fascicle, and fascicles, separated by the endotenon, join to form the macroscopic tendon¹. Tendon fibroblasts, or tenocytes, are found on collagen fibers allowing for the regulation of the extracellular environment in response to chemical and mechanical cues. (Reproduced, with permission of Elsevier, from: Silver FH, Freeman JW, Seehra GP. Collagen self-assembly and the development of tendon mechanical properties. J. Biomech. 2003 Oct;36(10):1529-33, Copyright 2003; and Wang JH. Mechanobiology of tendon. J Biomech. 2006;39(9):1563-82, Copyright 2006.)