Backscattered electron imaging: A new method for the study of cardiomyocyte architecture using scanning electron microscopy

Scanning electron microscopy (SEM) with secondary electron emissions is use ful for the study of cardiomyocyte architecture, however, the information i s limited from the cell surface. Whereas backscattered electron (BSE) emiss ion can give a high-resolution image of the specimen's intracellular struct ure after heavy metal staining. In this study, we applied BSE imaging analy sis to the study of the arrangement of cardiomyocytes in the myocardium. Th e tissue specimens from a normal fresh monkey heart, normal human heart obt ained at autopsy, and surgically resected tissue from a patient with old my ocardial infarction in the left ventricular aneurysmectomy were used. The t issue specimens were fixed in neutral formalin, treated with NaOH and then stained with Gomori's silver methenamine reagent followed by tannic acid an d osmium tetroxide. After dehydration and drying, the specimens were coated with carbon and examined by SEM with a BSE detector. In the tissue prepara tions, the A bands of sarcomeres were selectively stained with silver so th at the arrangements of subsarcolemmal myofibrils and the intercalated discs were clearly seen in the BSE images. In the left ventricular aneurysmal wa lls of old myocardial infarction, atrophied cardiomyocytes with disarray of subsarcolemmal myofibrils were observed. The results strongly suggest that BSE images are further applicable to the study of the architecture of card iac myocytes and their branches, and the arrangement of intracellular myofi brils in various diseased myocardium. (C) 2000 by Elsevier Science Inc.