In the gap region, however, the collagen molecules are oriented approximately parallel to the unit cell c-axis (slightly tilted in the opposite direction to that of the overlap tilt).

microfibrils, which each comprise five 1D-staggered, twisted collagen triple helix molecules.

examined the structure of the collagen gap zone by analyzing the 3D electron density map created from existing X-ray data of hydrated type-I collagen fibrils32.

Needles (~2 nm in width and ~10 nm in length, Supplementary Figs. 4 and 5) were observed at the tip of some platelets, which confirms previous observations2,12 and supports the hypothesis that the HAp platelets evolve from needle-like crystals.

After one hour of treadmill running, increased collagen synthesis was detected in both Achilles tendons