FEATURES OF THE STRUCTURE OF THE AORTA IN THE EARLY POSTNATAL PERIOD OF RAT DEVELOPMENT

Abstract

To study the morphofunctional parts of the thoracic and abdominal parts of the descending aorta at the early stages of the postnatal period of rat development. The experiment was carried out on male Wistar rats (n = 18), which were kept under standard vivarium conditions. The animals were taken out of the experiment on 7, 14 and 28 days of the postnatal period of development. For histological examination, fragments of the thoracic and abdominal parts of the descending part of the rat aorta were fixed, carried out according to the standard technique, and stained with hematoxylin and eosin, as well as with orsein. The structure of the wall of the thoracic and abdominal parts of the descending part of the aorta was assessed using a light microscope. To quantitatively characterize the morphofunctional state of the thoracic and abdominal regions of the descending part of the aorta, the thickness of the adventitia membrane was measured, as well as the thickness of the complex of the inner and middle vessel membranes. The results were processed using the statistical package Statistica 13.0 (Mann-Whitney U test). Data are presented as median and quartiles - Me (Q1; Q3). In the early postnatal period of rat development, a pronounced thickening of the aortic wall is observed due to an increase in the thickness of the complex of the inner and middle membranes in the thoracic region (from 7 to 14 days) and the abdominal region (from 14 to 28 days), as well as the thickness of the adventitia membrane (from 7 to 14 days) in both parts of the descending part of the aorta. On the 28th day of the postnatal period of rat development, the wall thickness of the thoracic and abdominal parts of the descending part of the aorta, as well as its structure, corresponds to that of sexually mature animals. Pronounced morphological changes in the wall of the thoracic and abdominal parts of the descending part of the aorta, including an increase in wall thickness, thickening and flattening of elastic fenestrated membranes, flattening of endotheliocyte nuclei and smooth myocytes, are observed in the first weeks of the postnatal period of ontogenesis in rats.