Figure 7. (a) Visualization of phospholipids after rapid-freezing and malachite green-acrolein-osmium-tetroxide freeze-substitution fixation. Liposome-like structures are seen in intercollagen spaces in predentin (PD). Collagen fibrils (Co) appear as electron-lucent areas. X81,000. (b) Sample treated with methanol prior to MG-acrolein- osmium-tetroxide freeze-substitution. MGA aggregates have totally disappeared from predentin (PD) after phospholipid extraction. X140,000.