The purpose of the research is to reveal microscopic, morphometric and ultrastructural changes in the vessels of the microcirculatory network of the fundal part of stomach under the influence of intracellular dehydration. Materials and methods. To simulate the intracellular dehydration, laboratory rats were provided with 1.2% sodium chloride solution as a drink and they were fed with conventional granulated food. Mild degree of cellular dehydration was achieved on the 10th day, an average degree – on 20th day, and a heavy degree of dehydration – on 30rd day of the experiment. Structural components were studied on histological sections stained with hematoxylin and eosin, Van-Hyson, and Malory. Semi-thin sections were stained with 1% methylene blue per 1% sodium tetraborate. Ultra-thin sections were contrasted with a solution of uranyl acetate and lead citrate according to Reynolds. Results. It was revealed that on the 10th day of the experiment the average area of the internal lumen cross-section of the arterioles and venules had no significant changes in comparison with the similar indices in the group of intact animals; on the 20th day this index exceeded the control on 10.19% (p<0, 0001) in arterioles, and on 5.68% (p<0.0001) in venules. On the 30-th day of cellular dehydration, the average area of the arteriolar lumen cross-section significantly exceeded the corresponding indicator of control rats on 14.31% (p<0.0001), the same indicator for venules increased to 7.82% (p<0.0001). At the ultramicroscopic level it was detected: the seal of cytoplasm, mitochondrial swelling and disruption of cristae structures, fragmentation areas and lysis of granular endoplasmic reticulum structures, reducing of ribosomes number on its membrane surface. Such changes occurred next to the narrowing of the lumen of the capillary as a result of edema of the endotheliocytes processes. Conclusions. The obtained results show an increase in cross-sectional area of the internal lumen of blood vessels with increasing the severity level of dehydration. The revealed ultrastructural transformations of the organelles of endothelial cells of the microcirculatory network capillaries of the stomach show a violation of their functional state and cause an increase in dystrophic changes in the cellular composition of the stomach tissues with their transition to destructive.
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