Fig. 3

BMP-2 (a), Osterix (b), and Osteocalcin (c) were detected in degenerated discs, even if μ-CT did not show calcification. ALP (d) was positive in herniated discs with evidence of calcification. In discs for which μ-CT indicated – or ± calcification, ALP expression was not detected or detected in only a few cells (e), whereas staining for Osterix (f) was positive in the same position. a and d are Pfirrmann grade IV discs, b and c belong to grade V, and e and f are grade III