Figure 7.

In situ hybridization of genes involved in regulatory processes. A. Runx2 at the osteoblast growth zone of the vertebral body endplates in non-deformed vertebral bodies (arrow). Notice no transcription in chordocytes. B. Runx2 transcription in intermediate vertebrae showed transcription in chordoblasts. C. Runx2 transcription in fused vertebrae, notice positive staining in the chordocytes and in areas with ectopic bone formation (arrow). D. Strong staining of runx2 in cells in the notochord of a fusion. E. Sox9 transcription chondrocytes of non-deformed vertebrae. F. Fused vertebrae had high sox9 transcription in intervertebral space. G. Higher magnification of cells expressing sox9 at the vertebral growth zone of a fusion. H. Sox9 was also expressed along the rims of ectopic bone formation. I. Mef2c transcription in hypertrophic zone in non-deformed vertebral bodies. J. Mef2c in fusing arch centra. Notice positive cells outside the hypertrophic zone (arrow). K. Mef2c in arch center narrowing down. L. Mef2c transcription at the growth zones blending with the arch centra. M. Mef2c positive cells in intervertebral space of an incomplete fusion (arrow). ND, non-deformed; IM, intermediated; FS, fused, nc, notochord; ns, notochordal sheath, eb, endbone; ec, ectopic bone. Scale bar = 100 μm.