Differential interference contrast microscopy of human atherosclerotic lesions.

Differential interference contrast microscopy was employed to study sections of human cerebral arteries and aorta. When this procedure was used to observe 0.5-mu-thick sections of plastic-embedded arteries, images were obtained with greater definition of detail than corresponding micrographs of the area using conventional bright-field microscopy. Since structures with different refractive indices are shown in geometric relief from one another, an apparent three-dimensional image is seen, which, together with the theoretically higher resolution and contrast achieved by this technic, gives an image with definition between conventional light and low magnification electron microscopy. The morphology of fatty streak lesions with aggregates of round and elongated lipid-filled cells was demonstrated, and clear images of different forms and sizes of intracellular lipid droplets were illustrated at magnifications around 1000. In atheromatous plaques, intra- and extracellular lipid droplets were observed, some with partially extracted cores or surfaces, as were amorphous lipid droplets coalescing with crystals whose centers had been extracted. We conclude that this optical accessory to a research photomicroscope is a valuable supplemental tool in studies on the morphology of atherosclerotic lesions.