Fig. 4

Mouse 3, Hemivertebra in the proximal lumbar spine (female mouse, 31.5 weeks old at the MRI, specimen X-ray, and histology) A-G: Soft X-ray images. A, B: specimen, C: 10 weeks, D: 13 weeks, E: 16 weeks, F: 22 weeks, and G: 27 weeks after birth. The HV is shown (arrow). In the middle thoracic spine, there are multiple malformed vertebrae with conjoined ribs. H, I: Histology of the hemivertebra (H × 40, I × 100). Approximately two-thirds of the HV surface is covered with the structured GP, and the remaining one-thirds is covered with cortical bone. The intervertebral space surrounding the HV contains normal intervertebral structures, including the NP, AF, and CEP. In the two NPs, young immature cells are observed, and the development of the NP seems to be delayed. The two NPs are separated by the CEP on the right side of the HV (arrowhead). Two vertebrae confining the HV on the convex side adjoin each other on the concave side. The GPs look thinner and insufficiently formed, and there is a CEP on these GPs but no NP or AF is observed (*). J: T1-weighted MR image. The contour of the HV is shown as a dark low signal intensity corresponding to the GPs and cortical bone. The hemivertebral body is slightly more intense, showing a bone marrow-rich content. The intervertebral space surrounding the HV was observed at high intensity. K: T2-weighted MR image. The bright high-intensity area is limited to the right part of the intervertebral space around the HV, which corresponds to the NP in the histology