KINETICS OF THE DEVELOPMENT OF THE MICROCIRCULATORY TRACT OF THE MYOCARDIAL COMPLEX (LV + IVS) IN THE PROCESS OF EARLY POSTNATAL ONTOGENESIS OF RATS WISTAR

Abstract

An electron-microscopic, optical and morphometric study of a series of negatives of the microvessels of the blood microcirculatory tract (MCT) of the myocardium of the complex «left ventricle + interventricular septum» (LV + IVS) of Wistar rats aged from birth to 45 days was carried out. In a series of electron microscopic images (50 negatives of (6.5 x 9) cm2 in size, obtained at a magnification of an electron microscope of 2000x ), the relative volumes (%), absolute volumes (μm3) and average daily growth rate (μm3/ day) of MCT, capillaries, complex of microvessels (venules + arterioles). The obtained digital morphometry data made it possible to determine the regularities of the development kinetics of MCT components in the myocardium of rats during their early postnatal development. It was established that in the time interval (birth to 45 days) of the postnatal development of Wistar rats, the structural and functional elements of the blood-flowing MCR of the myocardium gradually reach their final development. For 45 days after the birth of rats, the dominant component in the blood MCT of the myocardial complex (LV + IVS) is the capillary link. In the process of postnatal angiogenesis, the source of the formation of arterioles and venules in the blood MCT of the myocardium (LV + IVS) are the existing capillaries. Intensive development of the capillary link in the MCT of the myocardium occurs during the first 10 days after birth of rats. During this period of time, the average daily growth rate of the absolute volume of capillaries in the MCT of the myocardium increases (from 0.20 to a maximum of 0.915) x109 μm3 / day. Gradual development of the microvascular complex (arterioles + venules) and increase in their absolute volume in the MCT of the myocardium occurs during the first 25 days after birth of rats. During this period of time, the average daily growth rate of the absolute volume of the microvascular complex (a + v) increases ≈ 52 times (from 0.006 to a maximum of 0.310) x 109 μm3 / day. In the MCТ of the myocardium of newborn rats, the ratio of microvascular volume (a + v) / cap was 1:44.1. Within 45 days after the birth of rats, there is a significant increase of microvascular volume (a + v) / cap in the MCT to 1: 3.1.

Keywords

• angiogenesis,morphometry,capillaries,arterioles,venules.