Figure 6.

In situ hybridization of genes involved in the extracellular matrix. A. Col1a transcription observed in trabeculae and at the growth zones of vertebral body endplates of intermediate vertebrae. B. Col1a in osteoblasts extending from the growth zones of the vertebral body endplate in intermediate and C. fused vertebrae. D. Col1a transcription in the notochord of a fusion. E. Col2a transcription in chordoblasts of intermediate vertebrae (arrow). F. Col2a transcription increased as intervertebral space narrowed down. In addition, col2a was observed at the osteoblast growth zone at the vertebral body endplates (arrow). G. In fused vertebrae, most cells in intervertebral space expressed col2a and expression in the osteoblasts increased (arrow). H. Col10a transcription along the rims of intermediate vertebrae and in hypertrophic chondrocytes (arrow). I. Col10a was more expressed in areas with ectopic bone formation (arrow). J. Osteonectin in fused vertebral bodies. Notice transcription along the rims of the vertebral bodies as well as in chondrocytes (arrow). Stronger staining was observed in areas with ectopic bone formation. K. Osteonectin transcription in areas with ectopic bone formation. L. Osteonectin transcribing chondrocytes. M. Osteocalcin was expressed in chondrocytes and along the rims of fused vertebrae. N. Osteocalcin transcription at the growth zone of two vertebral body endplates in a fusion. Notice cells expressing osteocalcin abaxial in-between the vertebral bodies (arrow). O. Osteocalcin expressing cells blending with chondrocytes. Both osteoblasts and chondrocytes expressed osteocalcin in these areas. ND, non-deformed; IM, intermediated; FS, fused, nc, notochord; ns, notochordal sheath, eb, endbone; ec, ectopic bone. Scale bar = 100 μm.