[Ultrastructural changes in the pig heart following transport stress].

The myocardium of ten selected hybrid fattening pigs of different origin was examined by electron microscopy, immediately following lorry transport of something between 60 and 120 minutes. The animals were severely exhausted, and some of them had collapsed. While little information was obtainable from the histological findings, ultrastructural tests revealed multiple focal myofibrillolysis (destruction of I-band and Z-band). Oedematisation, loss of glycogen, and hydropic degeneration of mitochondria were processes additionally recorded from the muscular fibres. The terminal vessels exhibited hydropic endothelia swellings which narrowed vascular lumens, focal statis, and incipient thrombosis. Those changes suggested an involvement of the myocardium in the pathogenesis of transport death and justified the definition of those phenomena as "stress-caused cardiomyopathy" in the wider context of stress myopathies of swine.