Microscopic findings. Acute myocardial infarction: polymorphonuclear leucocyte infiltration (A). Hypercontracted myocardial cells with markedly short sarcomeres and anomalous, extreme thickening of Z lines and rexis of the myofibrillar apparatus into cross-fibre, anomalous and irregular, up to a total granular disruption (B). Diffuse stretching of the myocardium with elongation of the sarcomeres and nuclei (C). Reflow areas (D).