Figure 1. Experimental atheroma in aorta of hypercholesterolemic rabbits. Detection of macrophages, gelatinolytic activity, and expression of gelatinases MMP-2 and MMP-9. Top four panels illustrate consecutive sections of lesions in abdominal aorta; bottom four panels, in thoracic aorta. Top, Staining with cell-specific antibody (RAM-11) identifies numerous macrophages in intimal region. Same region contains gelatinolytic activity, as shown by processing of a consecutive section by in situ zymography (gelatinolytic activity is indicated by disappearance of green fluorescent gelatin substrate used to coat microscope slide). Immunostaining for MMP-2 and MMP-9 gelatinases shows colocalization of macrophage accumulations with MMP-9 expression but not with MMP-2. Bottom, Macrophages, MMP-9 expression, and gelatinolytic activity colocalize in a thoracic aorta lesion. Control specimens were processed without primary antibody (Ab). Bars=100 µm.