Proceedings of the International scientific and practical conference ―Cambridge Science and Education Conference‖ (May 15-17, 2026) / Publisher website: www.naukainfo.com. - Cambridge, United Kingdom, 2026. - 429 p.

114 Introduction A large number of works are devoted to the study of the morpho-functional state of the liver under the influence of various factors [1, 2]. After all, the liver plays a key role in metabolic metabolism, provides protection of the body from various types of intoxications, etc. [3]. At the same time, the authors often encounter discrepancies in the data obtained. This may be due to the initial state of the body, primarily the level of oxygen consumption (LOC) [4, 5]. Different LOC may underlie the differences in the body's response, which manifest themselves in different morpho-functional changes in liver tissue. In addition, almost no morphological changes in the liver parenchyma have been studied, taking into account the peculiarities of the body's ability to consume oxygen. The aim of our work was to investigate and compare structural changes in liver tissue in young rats with different levels of oxygen consumption. Materials and methods The study was conducted on 30 male Wistar rats aged 4 months. The rats were kept on a standard vivarium diet and under standardized conditions. The requirements of the European Convention for the Protection of Vertebrate Animals (Strasbourg, 1986) were met when working with animals. The rats were divided into 2 groups, depending on their LOC: Group I – animals with a low LOC, Group II – rats with a high LOC. Oxygen consumption of rats was determined on an empty stomach in a closed gas exchange research system (indirect calorimetry method). Oxygen consumption was calculated in ml per 1 minute per 100 g of body weight and adjusted to standard physical conditions. LOC is one of the key markers of the state of energy metabolism of the body [6]. Tissue samples were taken from the left lobe of the liver for histological examination. Histomorphometric analysis of liver tissue was performed using the software "Image J" [2]. Results and Discussion Significant differences in the structure of the liver parenchyma were found in rats with different LOC. Thus, in animals with high LOC, a significantly larger cross- sectional area of hepatocytes and their cytoplasm was observed by 19 and 22%,