Aernoud Fiolet

56 Chapter 2 Figure 2. Transitional phases of metastable to stable CCs. (Upper panel) in vitro phases of crystal formation are seen to form over weeks (bars = 10 μm). Modified with permission.16 (Lower panel) in an in vivo atherosclerotic rabbit model, ribbons of cholesterol crystals appear transiently to be evolving into plates (courtesy George Abela). The rate of change through each stage is affected by physiochemical environmental factors. The tissues were processed for scanning electron microscopy without ethanol dehydration to avoid dissolving the CCs. Instead, the tissues were dehydrated by vacuumwith minimal shrinkage. 20, 21 As LDL continue to accumulate in the endothelium, various forms of ox-LDL are released into the interstitial space where their fate depends on their size, the rate at, which they are deposited, and the rate at which they can be cleared by scavenger cells. If the rate of accumulation of lipoproteins is rapid and the rate of clearance is low, they may begin to coalesce and form into vesicles that may become richer in free cholesterol as the lipoproteins degrade, which then predisposes to the formation of free CCswithin them. 4,5 If the rate of accumulation of lipoproteins can be slowed and as the cellular environment of the vessel wall becomes more replete