Postnatal Changes in the Morphology of the Myocardium in Rat Ventricles

Background: Aging of the myocardium is a dynamic process which involves progressive loss of cardiomyocytes due to necrosis and apoptosis, interstitial fibrosis and reactive hypertrophy of the remaining vital cardiomyocytes. In our study, we investigated the postnatal changes in the myocardium of 15 adult male Wistar rats, distributed in the following age groups: 2 weeks, 1, 3, 6 and 12 months old. We used routine hematoxylin and eosin staining and Mallory’s trichrome stain. Results: Hypertrophy of the cardiomyocytes and accumulation of extracellular matrix proteins in the interstitial space in the aging myocardium were observed. The occurrence of these processes was more dynamic in the left ventricle as opposed to the right ventricle owing to the functional dissimilarities between the two ventricles and a more pronounced effect of afterload on the left ventricle.Conclusions: In conclusion, it can be stated that aging of the myocardium is a dynamic process, characterized by hypertrophy of the cardiomyocytes, reduced capillary density and increased deposition of collagen.