Freeze-etch study of collagen. I. Native collagen from tendon and lung of rats.

The freeze-fracture technique was used to study the fine structure of native collagen from rat tendon and lung. The collagen filaments were organized into a spiraled lamellar substructure within each fibril. Small particles, representing the broken ends of the collagen filaments, were found in nearly straight rows when the lamellae were broken tranversely. Filamentous connections were shown which span the interfibrillar matrix and unite all of the fibrils into a reticular network. The fibrils were coated with material that was greatly hydrated in vivo. Sublimation occurred more rapidly from some portions of the coating substance than from others, resulting in a banding pattern with a 610 A repeat distance.