Морфометрический анализ пренатального и постнатального созревания кардиомиоцитов крыс

Abstract

Проведено електронно-мікроскопічне, морфометричне дослідження кінетики розвитку ультраструктур кардіоміоцитів лівого шлуночка (КМЦ ЛШ) серця на етапах пре- та постнатального розвитку щурів лінії Вістар. Установлено, що в інтервалі t ϵ (12 діб ембріо- та 45 діб постембріогенеза) відбувається процес дозрівання КМЦ. На початку фази дозрівання КМЦ Vv мф = Vv мх = 3%. Наприкінці фази дозрівання КМЦ Vv мф = Vv мх = 40%. Запропонована формула для визначення ступеня зрілості КМЦ: G = (Vv мф + Vv мх) / 80%, де G – ступінь зрілості КМЦ, (Vv мф+Vv мх) – об’ємна частка МФ і МХ у дозріваючих КМЦ (%), 80% – об’ємна частка МФ і МХ у зрілих КМЦ; Проведено электронно-микроскопическое и морфометрическое исследование ультраструктур кардиомиоцитов левого желудочка (КМЦ ЛЖ) на этапах пре- и постнатального развития крыс Вистар. В интервале t ϵ (12 сут. эмбрио- и 45 сут. постэмбриогенеза), происходит процесс созревания КМЦ. В начале фазы пренатального созревания КМЦ Vv мф = Vv мх = 3%. В конце фазы созревания КМЦ Vv мф = Vv мх = 40%. Предложена формула для определения степени зрелости КМЦ: G = (Vv мф + Vv мх) / 80%, где G – степень зрелости КМЦ, (Vv мф+Vv мх) объемная доля МФ и МХ в созревающих КМЦ (%), 80% — объемная доля МФ и МХ в зрелых КМЦ; One of the most common objects for research in developmental biology, age related morphology, experimental medicine are laboratory mice and Wistar rats. Laboratory animals are investigated sufficiently detailed applying embryological, histological, physiological, biochemical and morphometric methods. It was determined, that ontogenesis regularities in laboratory animals and humans had certain similar features. The results of these researches enabled to develop postnatal life periodization of white rats and determine the age equivalents of rat and human. The aim of the study is to investigate kinetics of cardiomyocytes (CMC) development of the heart left ventricle in the process of prenatal and early postnatal ontogenesis of Wistar rats and use obtained data for specification of the cardiomyocytes maturation phase. The normotensive rats − Wistar male rats from vivarium of V.N. Karazin Kharkiv National University were used in research. The age of the animals was: 15, 20 days of prenatal development and 8-12 hours, 1, 5, 10, 15, 20, 25, 30, 35, 40 and 45 days of postnatal ontogenesis. Each age group included 5 animals. Electron microscopic studies determined that the parenchyma of trabecular and compact myocardium of the left ventricle in rat embryos consisted of moderately dehydrated dark cardiomyocytes in functional rest state. Light cardiomyocytes are able to contract and involved in proliferation. Dynamics of cardiomyocytes ultrastructure stated that the processes of mutual transformation of d-CMC ↔ l-CMC occurred in the myocardium parenchyma of embryos. Morphometric study of kinetics in cardiomyocytes ultrastructure development in the left ventricle of Wistar male rats at pre- and postnatal stages of animals development was carried out. It was determined that in the time interval (12 days embryo and 45 days of postembryogenesis) the process of cardiomyocytes maturation in the left ventricle occured. In the early phase of prenatal maturation of cardiomyocytes Vv mf = Vv мch = 3%. At the end of the cardiomyocytes maturation phase Vv mf = Vv мch = 40%. The formula for determining of the cardiomyocytes maturity degree is: G = (Vv mf + Vv мch) / 80%, where G is the cardiomyocytes maturity degree (Vv mf + Vv мch) – the sum of myofibrils and mitochondria volume fractions in mature cardiomyocytes (in %), 80% − the total volume of myofibrils and mitochondria in cardiomyocytes. The graphs of digital values Vv mf and Vv мch have «S»-shaped form, the points of inflection on these graphs correspond to the rats birth. Conclusions 1. Time borders of the maturation phase in the left ventricle of Wistar rats are: 12 days of prenatal and 45 days of postnatal development. The maturation of cardiomyocytes in the left ventricle is accompanied by simultaneous and monotonous increase of myofibrils and mitochondria volume fractions. In the interval of maturation cardiomyocytes phase, digital values of Vv mf and Vv мch increase from 3% to 40%. 2. In the process of embryogenesis, the periodic transformation d-CMC ↔ l-CMC in the myocardium of the left ventricle occurs. Only light cardiomyocytes of the left ventricle are able to proliferate, synthetize protein of myofibrils and mitochondria, physiological hypertrophy.