Figure 6: Collagen (blue colored fibers) in micromass cartilages as shown by Masson’s trichrome staining (a), and proteoglycans (orange-red color) in micromass cartilages as shown by safranin O staining (b). Higher magnification shows more details that collagen (blue colored fibers), cell size, and intercellular distance increase from week 1 to 4 in micromass cartilages (a). Proteoglycans were dominant at weeks 3 and 4 and were weakly expressed at weeks 1 and 2 (b). Rat knee articular cartilage served as a positive control for safranin O staining (b). M, meniscus; AC, articular cartilage; B, bone; mm, micromass; CL, Cruciate Ligament.