Light microscopy of cell-polymer constructs: (a) after 1 week of culture, extracellular matrix has formed and cells have migrated inside the
scaffold. Small pockets of non-degraded polymer remain (H&E, 100). (b) After 4 weeks of culture, the density of the extracellular matrix has
increased, and extensive calcification has occurred (H&E, 100). (c) After 4 weeks of culture, the extracellular matrix has become calcified
throughout the specimen (von Kossa staining, 200). (d) After 4 weeks of culture, collagen type 1 is present in both the outer and inner parts of the
scaffolds (immunostaining of type I collagen, 200).