Figure 2.

Light microscopic semiquantitative grading system (polychromatic staining). Normal (negative controls): closely packed long parallel arrays of intact elastic fibers; Grade 1: mild fragmentation of elastic fibers, a mild increase in collagen; Grade 2: widespread disruption and fragmentation of elastic fibers, a conspicuous increase in collagen; widespread loss of smooth muscle cells; Grade 3 (positive controls): large areas of the complete loss of elastic fibers, a conspicuous increase in collagen and ground substance and overall loss of smooth muscle cells.