Figure 6

Hearts Salmo salar L. Resin sections (1.5 μm) were stained with Toluidine blue. A); normal heart tissue, showing the various layers of the ventricle; epicardium (1), stratum compactum (2) and stratum spongiosum (3) together with endocardium (4). B) -H); ventricle from SAV-infected fish. Focal epicarditis (B; black arrow) and focal cardiomyocytic degeneration (C; arrowheads) could be observed at 14 dpi. D)-F); severe epicarditis and myocarditis (black arrows), together with multifocal degeneration of cardiomyocytes (arrowheads) was seen at 21 dpi. G) and H); hypercellularity and inflammation (black arrows) in the contact layer between compact and spongy myocardium was seen at 35 dpi.