Ultrastructural pathology of coxsackie A4 virus infection of mouse striated muscle

Electron microscopic examination of Coxsackie A4 virus-infected hind limb muscles of suckling mice showed generalized myositis with almost total loss of normal muscle cell architecture. Degenerative changes included dilatation of sarcoplasmic reticulum with concurrent disruption of myofibrils, presenting the appearance of dense amorphous masses in some areas; large accumulations of membrane-bound vesicles; swelling, distortion, and mineralization of mitochondria; increase in lipid deposits; pyknosis of the nuclei; edema and inflammatory infiltration. Virus particles were present in a number of different configurations in muscle fibers: individual particles or small accumulations within vacuoles, two-dimensional linear arrays between membranes, and three-dimensional crystalline arrays, usually in close apposition to sarcoplasmic reticulum or sarcolemma.