The structure of rat tail tendon fascicles.

Evidence is presented to support the view that the surface of a fascicle reflects the wave pattern of its constituent collagen fibrils. The wave pattern shows considerable variation within and between fascicles. Smooth continuous phase shifts in crimp angles and crimp lengths across the width and along the length of a fascicle are seen as explaining many of the varied crimp patterns seen. It is proposed that collagen fibril packing is a simple side-by-side aggregation with a degree of freedom in any direction in the register of the wave patterns.