Fig. 6.

Expression and localization of collagen I, collagen II, and protease nexin-1 determined by immunohistochemistry. Cryosections of 3-day mouse knee joints, 3-week neocartilage, and 3-week-old mouse femoral heads were incubated with antibodies to collagen II (A–C), collagen I (D–F), and protease nexin-1 (G and H) using identical antibody incubations and color development for each tissue. The region of the 3-day mouse knee joint depicted is the proximal tibial epiphyseal cartilage. Positive immunolocalization of proteins is indicated by brown staining and tissue histology and nuclear localization are indicated by blue-violet hematoxylin counterstain. No immunoreactive staining was observed when primary antibodies were omitted from either the rabbit or mouse IgG detection protocol. Representative images of mouse antibody immunodetection controls are shown (−1° Ab). Each scale bar represents 100 microns. Expanded regions of protease nexin-1 images reveal intense pericellular (open arrows) and cell-associated (arrowheads) staining.