In the control group of old untreated rats, all animals exhibited bundles of hypertrophied cardiomyocytes, the presence of pyknotic nuclei, focal hyper-eosinophilia of cardiomyocytes, as well as increased size of cardiomyocyte nuclei and the appearance of multinucleated cardiomyocytes (Figure 7). In some fields of view, individual nuclei were enlarged, from oval to round, hyperchromatic, and had a dense central longitudinal septum (Figure 7), and atherosclerotic changes were identified in the walls of large arteries (Figure 7). One rat, isolated mononuclear cells were identified in the myocardium (Figure 7).