The dissertation presents a theoretical generalization and a new solution to the scientific problem of establishing the structure of the right and left atrioventricular valves of the heart of white rats in normal and at different times of long-term exposure to opioids, which will create a morphological basis for the development of methods for preventing structural changes. drug agents. Histological examination revealed that on the inner surface (facing the ventricular cavity) of the valves of the heart of white rats endothelial cells are located tightly, contain many microvilli on the surface. On the outer surface of the valves (facing the atrial cavity) endothelial cells are located less densely compared to the layer of inner endothelium. The atrial surface of valves is smooth, the endothelial layer is more expressed in comparison with a ventricular surface. The ventricular surface is uneven due to the outgrowths from which the tendon strings begin. In this area under the endothelium are only a few elastic fibers. At the base of the valves, the endocardium is separated from the myocardium by a connective tissue base containing elastic, collagen and reticular fibers. Between them are blood vessels and nerves. The first signs of disturbance of the microstructure of the endocardium of the right and left atrioventricular valves of the heart are noticeable after 14 days of administration of nalbuphine to white rats. Over the next 28 days during the experiment, pathological changes increase and are manifested by a violation of the clear structure of the endocardium, its "mosaic" damage, defibering and fragmentation of connective tissue fibers, severe edema and increased amount of the main substance, diffuse sclerosis, vascular edema. Electron microscopic examination after 14 days of daily administration of nalbuphine revealed preserved endothelial cells with signs of intracellular edema, swelling of collagen fibers, loss of their divergence and homogenization of elastic fibers, indicating the beginning of defibering of the surface layers of the heart layers underneath. After 28 days of the experiment, changes in the shape of cellular elements, intussusception of the nuclear envelope, signs of apoptosis, violation of the integrity of the plasmolemma, which led to the release of organelles into the intercellular space, vacuolation of mitochondria and vacuoles with myelin-like inclusions. Damage to the tight closing contacts between endothelial cells and the fibrous basement membrane was observed, and the expansion of the connective tissue base was noted. In the later stages of the experiment (after 42 days) revealed partial or complete destruction of the plasmolemma of endothelial cells, deformation of the nucleus with thickening or destruction of the nuclear envelope, expansion of the intercellular lumen due to edema, destruction or compaction and homogenization of basement membranes, elastic fibers. Morphometric analysis of white rat heart valves showed a decrease in the length of the septal sash by 21.9%, parietal sash by 13%, corner sash by 13%, width of the septal sash by 12.1%, wall sash by 7.1%, angular sash by 14 , 1% after 42 days of administration of nalbuphine. Statistical analysis of the results of the study showed that the difference between the length and width of the wings of the tricuspid valve of white rats of experimental and control animals is significant. After 6 weeks of the experiment, the endothelial layer was thinned by 50.8%, the subendothelial layer by 28.2% and the musculo-elastic layer by 44%.
