Comparative morphofunctional characteristics of the myocardium of fetal ventricles and newborn rats born at physiological pregnancy

Background. It is known, that the obtained research results are usually compared with the indicators of the physiological norm (control groups). In the literature, there are numerous data on the morphological state of the heart of adult rats of the WAG population, while similar information on fetuses and newborn rats is not so numerous and the available data have some discrepancies. Objective. On the experimental model, to study the morphofunctional state of the heart of fetuses and newborn rats born during a physiological pregnancy, for the further use of the research results as a comparison group when identifying the morphofunctional features of the heart of the posterity obtained from a complicated pregnancy. Methods. In the experiment on rats of the WAG population, whose pregnancy was physiological, 3 observation groups were formed: hearts of fetuses (PL), one-day-old newborns (HB1D) and seven-day-old newborns (HB7D). Histological and morphometric research methods were used, followed by statistical processing using Student's t-test and Mann-Whitney U-test. The significance of the differences between indicators was accepted at the level of significance <0.05. The experiment was conducted in accordance with the Directive of the European Parliament of the Council of the European Union "On the protection of animals used for scientific purposes" (2010) and Good Laboratory Practice standards. Results. The morphological state of the myocardium of one-day-old and especially seven-day-old newborn rats has significant features, both from the side of the parenchymal and stromal-vascular components of the myocardium of the left and right ventricles of the heart, which should be taken into account when forming control groups, as manifestations of childbirth stress and postpartum adaptation. Conclusion. The morphological picture of the myocardium of rat fetuses corresponds to modern ideas about the physiological norm and can be used as a comparison group when studying the influence of maternal pathology on the fetal heart. The results of the research indicate the incorrect use of rat fetuses for the control group in studies, the material of which are newborns.