Morphological changes in the liver, as the main organ in which Opisthorchis felineus is localized, according to the literature, are characterized by significant structural differences in the acute and chronic phases of the disease. Comparative characteristics of the morphological changes in the liver in different phases of opisthorchiasis in the experiment in rabbits, such as Oryctolagus cuniculus, was not carried out. To simulate the acute and chronic phases of invasion, the animals were divided into two observation groups. The histological material was processed by standard methods, liver tissue sections were stained with hematoxylin and eosin and according to Van Gieson to identify connective tissue structures. Histological preparations were studied by the methods of light-optical microscopy with immersion, video microscopy with morphometry. As a result of the study, it was found that in the acute phase of opisthorchiasis, the general infiltration of the portal tract area prevails compared to the infiltration of the bile duct wall, in the chronic phase, the thickness of the infiltrate of the bile duct wall approaches the total values. The cellular composition of infiltrates is characterized by the presence of lymphocytes, fibroblasts, epithelioid cells and cells of foreign bodies in both phases, if macrophages predominate in the acute phase of invasion, then fibrocytes and mast cells predominate in the chronic phase. Hepatocytes in the acute phase have disturbances in the tinctorial properties of the karyolemma and cytoplasm, mainly due to grain segregation. In the chronic phase of opisthorchiasis, polyploid hepatocytes are found. The connective tissue of the portal tract region in both phases quantitatively predominates in comparison with the connective tissue of the region of the boundary plates. The maximum amount of connective tissue in the area of ​​the portal tract in the chronic phase increases by 4.4 times compared with the acute phase of the parasitic disease. Thus, morphological changes in the liver of rabbits in different phases are characterized by both commonality and significant differences, consisting in different cellular composition of the invasion zone, the amount of connective tissue formed in different areas of the organ, and changes in hepatocytes.

There are many preconditions for changes in erythropoiesis and leukopoiesis, changes in biochemical parameters of blood, hemostatic system in animals and humans under conditions of opisthorchiasis invasion. The purpose of the study was to analyze morphological and biochemical changes in the blood system in chronic opisthorchiasis using an experimental model of Oryctolagus cuniculus. The experiment was carried out on rabbits (Oryctolagus cuniculus) with modeling of chronic opisthorchiasis. The invasive dose was 50 Opisthorchis felineus metacercariae. The animals were divided into a control group (n=10) and an observation group (n=10). The morphological blood picture wich was studied by the standard method was compared with the previously obtained results of its biochemical analysis for the content of lactate dehydrogenase, muscle creatine kinase, aspartate aminotransferase, alanine aminotransferase and uric acid. It was established that 1,5 years after infection of rabbits in the observation group, structural heteromorphism of leukocytes is manifested. Pseudo-eosinophils had toxic granularity in the cytoplasm. In 19,5% of pseudoeosinophils, both stab and segmented, vacuolization of the cytoplasm was noted. A significant number of forms of lympholysis (shadows of Botkin-Gumprecht-Klein) was found – 9,6% per 100 leukocytes. In the study of erythrocytes, the presence of poikilocytosis was established; the most common were acanthocytes, dacryocytes. In rabbits of the control group and the observation group, the differences in blood pH are non-significant. Microscopic observation in a thick blood drop revealed that in the control group erythrocytes in vitro retained passive mobility for 59,8±15,2 seconds, in the observation group this figure was 42,6±7,5 seconds, erythrocytes formed aggregates. The blood clotting time in the control group is 101,9±32,1 seconds, and in the observation group – 194,8±35,2 seconds, the differences are significant. A change in the tinctorial properties of the platelet chromomere was noted. Thus, in rabbits with experimentally induced chronic opisthorchiasis, morphological changes in blood cells are observed, a decrease in the activity of the coagulation system with associated changes in its biochemical parameters, which contributes to a more detailed understanding of the pathogenetic mechanisms of changes in the blood system in chronic opisthorchiasis.