Fig. 8

Locations at which collagen fibrils cross over have distinct mNG-Col1α2 fluorescence intensity maxima which can exist before a crossover event. (A) Frames from an mNG-Col1α2 fibril deposition movie. Points of fibril-fibril crossover locally increase in intensity following crossover to give dark foci representing a local accumulation mNG-Col1α2 (blue arrows). Black arrows track the end of a fibril which crosses at this point. Alternatively, fibrils can cross over at points where accumulations pre-exist (red arrow). Intersecting fibril tip (white arrow) 5 min per frame. Time stamps are included on each frame. Scale = 2 μm. (B) Zoomed in view of crossover event. Dark foci of mNG-Col1α2 accumulation can pre-exist along a fibril. A new growing fibril entering the frame transitions specifically through these points (red circles) suggesting a predetermination of the location of these crossover nodes or fibril growth along a faint unresolved fibril which is already crossing over. Images were acquired at 5 min intervals. 12 frames per hour. Time stamps are included on each frame. Scale = 10 μm.