Heart and skeletal muscle inflammation (HSMI) disease diagnosed on a British Columbia salmon farm through a longitudinal farm study
A) Severe diffuse/ infiltrative panmyocarditis, involving the epicardium (arrows) and the compact layer of the myocardium (stars). The spongy layer is also involved in widespread inflammatory nodules (arrowheads). Bar scale: 500μm. B) Solid line inset of Fig A. The inflammatory infiltrate comprises mononuclear cells (lymphocytes and macrophages) in both epicardium (arrows) and compact myocardium (stars). Along with the inflammation, myocardial degeneration and necrosis are also visible (arrowheads). Scale bar: 100μm. C) Dashed line inset of Fig A. Multiple foci of endo-myocarditis (arrows) and myocardionecrosis (arrowheads) in the spongy layer of the myocardium Scale bar: 100μm. D) Severe diffuse zonal degeneration and necrosis in liver. Scale bar: 250μm. E) Severe diffuse infiltrative myositis in skeletal muscle. Note the white portion of the muscle (star) completely unaffected by the inflammatory reaction. Scale bar: 500μm. F) Inset of Fig E. Severe myonecrosis (along with some regenerating muscle cells) and infiltrating mononuclear cells inflammation are evident. Scale bar: 100μm.