Mouse Shoulders at Baseline, 14, 29 and 45 weeks post rotator cuff injury, 5× (top panel) and 10× (bottom panel) power. a. Baseline: round articular surface with no areas of flattening, few mitotic figures superficial to tidemark, dense subchondral bone. b. 14 weeks: Some flattening of articular surface, reactive layer with mitotic figures superficial to tidemark, marrow space closer to osteochondral junction. c. 29 weeks: Pitting of articular surface, hypercellular throughout with overall depletion of articular cartilage, tidemark difficult to distinguish, further marrow infiltration. d. 45 weeks: Loss of sphericity, disorganization of cartilage with tidemark inconsistently visible, marrow proliferation with minimal subchondral bone.