Observation on the Crimp Structure in Rat Tail Tendon Using a Transmission Electron Microscope

Crimp structure in young adult rat tail tendon was observed in a transmission electron microscope using the ultra-thin sectioning method to find that the sharp bending of the collagen fibril caused the crimp structure. The crimp angle was found to change discretely with the bundle which was composed of several hundred collagen fibrils, and to be smaller in the deeper region than in the surface region of the tendon. Such results supported the sequential straightening and loading model to explain the “toe region” behavior in the stress-strain curve of the tendon.