Nowadays, modelling in clinical and experimental urology became one of the main methods of scientific investigation that allows advancing the understanding of nodular questions in particular morphofunctional disorders that occur during ureterolithiasis and also explaining and analyzing ways of lithokinetic and litholytic therapy of complex calculi of ureter. The aim of the investigation is to study pathomorphological and immunohistochemical changes of histological structure of ureter’s wall in obstruction area during 7-8 days and after eradication of previous obstruction of calculus imitator during 7 days. Materials and methods. Experimental investigations for modelling of obstruction of ureter by concrement imitator were done on 48 outbred rats with body weight from 2,8 to 3,1 kg with further morphological investigation of ureter’s wall condition in area of obstruction on the seventh-eight day. Results. Proposed experimental model of ureterolithiasis in lab animals determines the condition of complex calculi of ureter. It allowed studying factors which assist in passage of foreign body from ureter and also it can be observed possible morphofunctional and structural changes which are similar to those that are present in patients who have calculi of ureter. Pathohistological investigation of ureter’s wall during experimental study during 7-8 days detected the next peculiarities of pathological changes: Dystrophy and necrosis in epithelial layer of ureter with expressed desquamation of cells of transitional epithelium has been determined. Dystrophic changes and necrosis in submucosal and mucous layer with presence of diffuse and focal leukocytic infiltration have been presented. Dyscirculatory changes in vessels of microcirculatory bed, perivascular swelling, focal hemorrhage have been presented. Dystrophic changes and minor focal necrosis of myocyte in muscular layer of ureter, swelling and inflammatory changes in connective tissue between of fascicles of muscular fibers have been also established. The second stage of pathomorphological investigation was microscopic investigation of ureter’s wall on the 7th day after eradication of previous obstruction 7-8 days. Histological investigation showed the next peculiarities: Simple minor foci of necrosis have been determined, dystrophic changes decreased significantly according to duration and severity, multiple foci of regeneration has been determined. Moderate expression of inflamed infiltration has been presented of focal character with cellular content of lymphocytes. Moderate swelling and sclerosing of perivascular spaces has been kept, unexpressed defects of hemomicrocirculation like stasis, red cell adherence have been determined. Dystrophy of ureter’s wall has lesser expression but there are focal sclerotic changes due to proliferation of connective tissue components. Conclusions. When concrement is anchored in the lumen of ureter more than 7 days, there are changes which assist in increased traumatization of ureter’s wall during endoscopic operation. Long-lasting placement of calculus in ureter is an additional factor that requires use of therapeutic methods that minimally traumatizes wall of ureter, especially contact lithotripsy (size, location and density of calculus is not principal factor).
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