Figure 5.
Electron micrographs of ultrastructural and EM-TUNEL observations on the cardiomyocytes of nontransgenic and transgenic mice treated with DOX. A−D and E−F represent the results of conventional electron microscopy and EM-TUNEL, respectively. Saline-treated nontransgenic myocardium showed normal ultrastructure (A). DOX-treated nontransgenic myocardium showed cytoplasmic vacuolization and mitochondrial damage (B) and myofilament disarray with loss of Z-band (C). However, no obvious ultrastructural changes were found in the DOX-treated transgenic mice (D). EM-TUNEL revealed fragmented DNA in the condensed chromatin structure (arrows) in the cardiomyocyte nucleus of nontransgenic (E), but not in the transgenic mice (F). Mf, myofiber; Mt, mitochondria; Nu, nucleolus. Original magnifications, ×15,000 (A−D) and ×20,000 (E and F).