Figure 6.

Granulation tissues in treated defects versus chondral/subchondral tissues in control defects at 21 days post-operative. Panels show collagen type I-immunostained/iron hematoxylin counterstained histology images at 1.25x (A-B, G-H) and 40x magnification (C-F, I-L). (A-F) Treated repair tissues from representative 150K and 10K-treated defects contained apoptotic (a), neutrophil-rich (n), neutrophil+stromal (ns) and stromal (s) tissues. Control tissues from representative proximal and distal defects contained fibrochondrocytes (fc) above the osteochondral junction (I, K), and subchondral chondrocytes (sc) or hypertrophic chondrocytes (htc) below the osteochondral junction (J, L). At the articulating surface of the control defects, fibrochondrocytes and are identified by strong collagen type 1 expression and flattened morphology.