Introduction. The high prevalence of kidney diseases caused by urinary tract obstruction has led to the need for experimental studies of the dynamics of pathological processes in their lesions. Despite the fact that the general patterns of development of obstructive uropathy are known, the features of renal tissue damage, in particular structural and molecular biological changes in this pathology, remain insufficiently studied.
Objective: to study the dynamics of changes in the phenotype of epithelial cells of the nephron of an obstructive kidney with unilateral ureteral obstruction using an experimental model.
Materials and methods. The experimental study was carried out on the basis of the Rostov State Medical University. The model of unilateral ureteral obstruction was reproduced in adult rabbits. The studies were carried out on the 7th, 14th and 21st days of complete obstruction of the left ureter. Immunophenotyping of obstructive kidney tissue samples was performed for markers of epithelial phenotype (cytokeratin 7, E-cadherin) and mesenchymal phenotype (vimentin, α- smooth muscle actin).
Results. The sequence of changes in the phenotype of nephron epithelial cells during ureteral obstruction has been established. The first signs of an epithelial-mesenchymal transition (EMT) appear by day 7 in the form of a decrease in visualization of markers of the epithelial phenotype. On the 14th day, the expression of both epithelial and mesenchymal markers is noted. Significant changes in the phenotype of nephron epithelial cells: loss of epithelial markers (cytokeratin 7, E-cadherin) and the acquisition of mesenchymal markers (vimentin, α- smooth muscle actin), are noted by the 21st day of the
experiment.
Conclusion. An experimental model of unilateral ureteral obstruction revealed the transformation of the nephron tubule cell phenotype from epithelial to mesenchymal.

Keywords: Immunophenotyping, unilateral ureteral obstruction, epithelial-mesenchymal transition, experimental model, obstructive uropathy