Figure 1.

Schematic overview of layered distribution of appropriate exogenous stimuli. The pseudostratified structure of articular cartilage (the three layers) and their cellular and molecular components listed in the left panel. Appropriated exogenous stimuli added into corresponding layer listed in the right panel (blue arrow). (A) Tangential zone; (B) transitional zone; (C) deep zone. BMP = bone morphogenic protein; FGF = fibroblast growth factor; LOXL2 = lysyl oxidase–like 2; TGF = transforming growth factor; TMNO = trimethylamine N-oxide.