Figure 4

Fixing and staining with PMA increases X-ray contrast but fails to fully penetrate a whole bovine disc and causes major structural changes. Whole intervertebral disc unstained (a,c,e) and stained with PMA for 2 months (b,d,f). Radiograph (a), tomography slice (c) and associated line profile (e) show that X-ray attenuation is low and no structural features were resolved in unstained IVDs. Attenuation and contrast are improved with PMA staining (b,d,f) although there are still some unstained regions shown in red (g–i). Rendered tomogram (g) clipped to show radial slice (i). Fixing and staining caused visible structural changes (j).