[Dynamics of necrotic changes in skeletal muscle in the prolonged crush syndrome]

Forms, dynamics of and relationships between necrotic changes in the skeletal muscles in the early period of the crush syndrome, following 9-hour compression of the soft tissue of the dog's thigh and 2 -- 7 hours after removal of the press are considered. Two interdependent forms of necrosis of muscles have been established -- diskoid and coagulative. Electron-microscopy studies showed that discoid necrosis of muscular fibres began with the lysis of the myofilaments of isotropic disks and Z-strips with subsequent destruction of myofibrils and outcome into myolosis. The peculiar feature of this form of necrosis was nearly complete absence of lysosomes. In a light microscope discoid necrosis was revealed as clear-cut transversed streaky fibres. Morphologically, coagulation necrosis was manifested on the ultrastructural level by formation of myofilic conglomerates consisting of overcontracted myofibrils, these being subjected to gradual fragmentation and splitting by hydrolases of leukocytes and macrophages. Discoid necrosis predominated in the muscles prior to the removal of the press and apparently developed because of ischemia. Coagulation necrosis of myofibrils was observed mostly following re-vascularization and might be one of outcomes of discoid necrosis.