Fig. 4. Chondrogenic nodules isolated from EBs showed expression of marker proteins characteristic for mature and hypertrophic cartilage. Nodules were cut from 5+16 d EBs, and 10 µm cryosections were analyzed by immunostaining for collagen II (A), osteopontin (B), bone sialoprotein I + II (C) and collagen X (D). Interference contrast microscopy pictures (E-H) demonstrate the typical round-shaped morphology of chondrocytes. Bar, 100 µm.