Text Box: EXPRESSION OF TRANSFORMING GROWTH FACTOR-Β1 IN CHILDREN WITH CONGENITAL HYDRONEPHROSIS YI YANG，SHIJUN JI, GUOGUI ZHAO Department of Pediatric Surgery and Major Laboratory of Health Ministry for Congenital Malformation, 2nd Clinical Hospital, China Medical University, Shenyang, China Purpose: To detect the expression of transforming growth factor-β1(TGF-β1 ) mRNA and protein in children with hydronephrosis and evaluate the role of TGF-β1 in the chronic renal damage in congenital hydronephrosis. Methods: We studied the expression of TGF-β1 mRNA and protein in renal parenchyma, renal pelvis and pelvic ureteral junction (PUJ) from 15 children with congenital hydronephrosis by immunohistochemistry and in situ hybridization methods. Results: The expression of TGF-β1 increased in the affected renal parenchyma, pelvis and PUJ. The expression of TGF-β1 protein was mainly localized in the plasma of proximal tubular cells. There was also positive expression in a few renal glomerular epithelium, mesengial cells and distal tubular cells. The expression of TGF-β1 mRNA was mainly distributed in the cell nucleus of proximal tubular cells. Positive granules were also seen in a few renal glomerular mesengial cells and parietal cells. The expression of TGF-β1 mRNA and protein was localized in the muscle cells, spindle cells and collagenous fibers in the pelvis and PUJ of the affected kidney. Conclusions: The expression of TGF-β1 increased in kidney with congenital hydronephrosis. The increase of TGF-β1 expression might related to the chronic renal damage and renal interstitial fibrosis caused by hydronephrosis. Key words: congenital hydronephrosis transforming growth factor 1718