Figure 4: Histology was used to evaluate chondrogenesis of expanded SDSCs (A) and chondrocytes (B) in a pellet culture system after a 14-day serum-free chondrogenic induction. Alcian blue staining (AB, blue color) and Safranin O staining (SO, red color) were used to detect sulfated GAGs, and immunohistochemistry staining (IHC, brown color) was for collagens I, II, and X. The scale bar is 800 μm.