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A comparative light-microscopic morphological study of the postnatal changes in the myocardium of the left and right ventricles in rat

G. Kotov, A. Iliev, B. Landzhov, L. Jelev, I. Dimitrova, D. Hinova-Palova


According to literature data, age-related remodelling of the myocardium is related to the development of hypertrophy of the cardiomyocytes and interstitial fibrosis. In the present study, we observed accumulation of collagen in the walls of the vessels, interstitium and perivascular zones in Wistar rats from various age groups. Normally, the bundles of cardiomyocytes and the separate cells are surrounded by thin layers of peri- and endomysium. In the aging myocardium, hypertrophy of cardiomyocytes, transformation of fibroblasts into myofibroblasts and accumulation of extracellular matrix proteins in the interstitium are observed. Histological analyses of aging rat hearts show progressive loss of cardiomyocytes due to necrosis and apoptosis. Thus, preserved cardiac muscle cells undergo a process of compensatory hypertrophy. In our study, we investigated 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 haematoxylin and eosin staining and Mallory`s trichrome stain in order to analyse morphological changes in the aging myocardium in the wall of the left and right ventricle, as well as changes undergone by cardiomyocytes. In conclusion, it can be stated that by aging, heart morphology becomes impaired at organ level, as well as at individual cardiomyocyte level. Aging of myocardium is a dynamic process, characterized by hypertrophy of cardiomyocytes, reduced capillary density and increased deposition of collagen. Considering the functional dissimilarities between the left and right ventricle (a more pronounced effect of the afterload on the left ventricle), processes in the left ventricle follow a more dynamic pattern and reactive fibrosis occurs earlier. Changes in the right ventricle occur at a relatively smooth pace.

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About The Authors

G. Kotov

A. Iliev

B. Landzhov

L. Jelev

I. Dimitrova

D. Hinova-Palova

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