MACRO- AND MICROSTRUCTURAL LIVER ARRANGEMENT IN WHITE RATS IN HEALTH

Normal weight of the rat liver is 11-16 g in mature animals, and 6-8 g in immature animals. It consists of 6 lobes: right lateral, left lateral, right central, left central, caudate lobe and additional lobe. Rat liver is externally covered with connective tissue capsule, which is tightly fused with the visceral layer of the peritoneum. The ligament apparatus is poorly pronounced. On the visceral surface, there is a porta hepatis with portal vein, own hepatic artery and hepatic ducts forming the common bile duct. Rats have no gallbladder. The internal structure of the liver is formed by parenchyma and stroma. The liver parenchyma is represented by hepatic lobules. Hepatic lobules have polygonal 5-6- sided shape, and consist of hepatic tubules and interlobular sinusoidal capillaries. The center of the lobule is the central vein. A small space called the space of Mall is found around the stromal elements of triads. Between the classical hepatic lobules, layers of loose connective tissue are found, in which the components of the hepatic triad are located, such as branches of hepatic artery, portal vein, lymphatic vessels and bile ducts. Fibroblasts, as well as solitary lymphocytes and macrophages are located in the cellular composition of loose connective tissue of the hepatic triads. Hepatic tubules are formed by hepatocytes, and are located in the radial direction. Hepatocytes are polygonal in shape, they are located in tubules in two rows, and are connected to each other by desmosomes. Hepatocytes are heteromorphic depending on the hepatic lobe and the region, and are found to be mostly uniform in their shape, intensity of cytoplasm coloring, and size within a specific region of the lobule. Interlobular connective tissue trabeculae are poorly developed. Margins of classical hepatic lobes were determined by the location of portal triads, hepatic plates and sinusoidal capillaries, which had a radial direction, from the central vein to the portal tracts.