The Rat Heart in the Prenatal and Postnatal Periods of Ontogenesis

Rats are the most common laboratory animals that are used in experiments to evaluate the cardiotoxic and, particularly, teratogenic effects of therapeutic agents. For correct interpretation of results of experimental studies, it is necessary to have a detailed understanding of the specific features of the development and structure of the heart of laboratory animals. The cardiac morphogenesis in rats, compared with that of humans, has the following specific features: (1) the peak of proliferative activity of cardiomyocytes occurs in the late stages of the prenatal period of ontogenesis, (2) the transition of the myocardium from hyperplastic to hypertrophic growth occurs in the early postnatal period of ontogenesis, and (3) the hypertrophic type of myocardial growth consists in the formation of cardiomyocytes with several diploid nuclei (multinucleated cardiomyocytes).