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. Author manuscript; available in PMC: 2022 Oct 1.
Published in final edited form as: Mater Sci Eng R Rep. 2021 Jul 30;146:100641. doi: 10.1016/j.mser.2021.100641

Fig. 8.

Fig. 8.

(A) Hierarchical structure of collagen demonstrating the collagen molecule (M), fibril (F), and proteoglycan (PG) structures subject to variable deformation, tendon strain (εT), fibril strain (εF), and molecule strain (εM) for different structural levels. Reprinted from Progress in Material Science, Vol. 52. P. Fratzl, R. Weinkamer, Nature’s hierarchical materials, 1263–1334, 2007, with permission from Elsevier [577]. (B) Confocal reflectance microscopy image of representative collagen microstructure metrics including pore size (P), fibril diameter (D), and orientation (θ). Scale bar = 20 μm.