MORPHOMETRIC CHARACTERISTICS OF CARDIOMYOCYTIC POPULATIONS OF THE FORMING PARENCHYMA MYOCARDIUM IN THE PROCESS OF POSTNATAL CARDIOMYOGENESIS

Zagoruyko G. E., Zagoruyko Yu. V., Filatоvа V. L.

MORPHOLOGY

Scentific article

In the study, Wistar rats were used: 15–16 and 20–21 daily embryos, newborns, 2.5, 5, 7.5, 10, 12.5, 15, and 20 day old rats. The absolute volume of the myocardial parenchyma (V pair, μm3 ) in the complex (LV + IVF) was determined by the formula: V pair = m. Pair / ρ. Here: mpar – mass of the parenchyma (mg); ρ = 1.05 g / cm3 = 1.05 mg / 109 µm3 – the average value of the density of the myocardium. The number of CMC (N cmc) in the myocardial parenchyma (LV + IVF) was determined by the formula: N cmc = Vpar / V cmc. Here: V cmc is the average volume of CMC (μm3 ). As a result of the research, it was established that the growth of mass and volume of the myocardial parenchyma in the complex (LV + IVF) is provided by the coordinated interaction of the functions of 3 populations of CMC. The population of the 1-st d-CMC consists of myocytes, which are in a state of physiological rest. The number of this population increases in the process of embryonic cardiomyogenesis. 1-st d-CMC is necessary for the subsequent postnatal development of the myocardial parenchyma. The activation of the contractile function of d-CMC occurs after the birth of rats. Within 7.5 days, as a result of the transition, the 1-st d – CMC→1-st l-CMC, the population of the 1st d-CMC decreases to zero. The 1-st l-CMC population provides contractile heart function. These CMCs are capable of reproduction and in the process of proliferation they cause an increase in the number of myocytes in the myocardial parenchyma. Within 2.5 days after the birth of rats, the number of population 1 l-CMC reaches a maximum, and then decreases as a result of a decrease in the number of CMC capable of proliferation. By the 15th day after birth, almost all CMC rats become two-nuclear as a result of the polyploidy process. The number of binuclear CMC in the myocardial parenchyma increases within 15 days after birth of rats from 5% (newborns) to 100% as a result of polyploidy. The 2nd CMC population provides the contractile function of the heart throughout the postnatal life of rats. The CMC synthesis apparatus performs continuous biosynthesis of ultrastructures. This leads to a monotonous increase in the mass and volume of CMC, regardless of their functional state and belonging to one of three populations of myocytes, which form and form the myocardial parenchyma in the complex (LV + IVF) during postnatal cardiomyogenesis.

cardiomyogenesis, growth, proliferation, polyploidy

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«Bulletin of problems biology and medicine» Issue 4 Part 2 (147), 2018 year, 282-286 pages, index UDK 612.172 : 611.127-018

10.29254/2077-4214-2018-4-2-147-282-286