ULTRASTRUCTURE OF RAT ATRIAL TISSUE AFTER EITHER PERFUSION-FIXATION OR IMMERSION-FIXATION BOTH IN-VIVO AND IN-VITRO STUDY - COMPARISON OF METHODOLOGICAL RELIABILITY

The present study compares, from a morphological point of view, the po ssible differences between perfusion- and immersion-fixation technique s performed on rat myocardium in order to evaluate their reliability. The data we obtained showed that when the two techniques are carried o ut with particular care, they do not present significant differences i n tissue preservation. Furthermore, we also evaluated the ultrastructu re of rat myocardium at the end of in vitro experiments. In this case, signs of subcellular changes, such as vacuolar degeneration, swollen mitochondria, intermyofibrillar myelin-like figures and enlargements o f non specialized junctions of the intercalated discs can frequently o ccur. So, our results indicate that the morphological integrity of myo cardium is not completely preserved during in vitro investigations.