The hepatic stellate cell is one of the cell types responsible for the abnormal production of extracellular matrix proteins in liver cirrhosis. Stellate cells are also mentioned in other organs such as pancreas, colon and the kidney. In kidney few data are known about these cells. Renal disease is characterized by the progressive decline of renal function and by an increase in fibrosis in the glomeruli and in the tubulointersitial compartment. The aim of this project is to accurately describe the characteristics of quiescent and activated renal stellate cells, their distribution in the renal cortex and their potential role in the development of tubulointerstitial and glomerular fibrosis in the rat. Morphological characterization such as the storage of retinyl esters, the presence of intermediate filament- and other proteins typical for (liver) stellate cells are studied by immunohistochemistry and immunofluorescence. The activated real stellate cells will be studied in 2 experimental rat models: the adriamycin model for glomerulosclerosis and the aristolochic acid model of tubulointerstitial fibrosis. Together with the activation of renal stellate cells the EMT (Epithelial to Mesenchymal Transition) process plays en important role in renal fibrosis. EMT is a process of reverse embryogenesis in which renal epithelial cells lose their ephitelial phenotype and acquire mensechymal characteristics. the distribution of CRBP-1 is indicative in this proces.