A rapid method for the detection of early stages of atherosclerotic lesion formation.

A simple, rapid technique for detecting early changes in the arterial vessels of rats and rabbits fed an atherogenic diet is described. After perfusion fixation, the descending thoracic aorta was cytochemically stained with oil red O to detect intracellular lipid and with Hoechst 33342 dye to detect nuclear DNA. The vessels were whole mounted and the luminal surface examined en face using both transmitted light and epifluorescence microscopy. With this technique it is possible to identify and quantitate mononuclear cells adhering to the vessel wall, determine the distribution and number of intimal foam cells within the intima, and determine the mitotic index of the endothelium. Tissue samples can be quickly prepared using this technique, thus allowing rapid analysis of the influence of various substances on the early stages of atherosclerotic lesion formation in animals fed an atherogenic diet.