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A complex of cells consisting of juxtaglomerular cells, extraglomerular mesangium lacis cells, the macula densa of the distal convoluted tubule, and granular epithelial peripolar cells. Juxtaglomerular cells are modified smooth muscle cells found in the walls of afferent glomerular arterioles and sometimes the efferent arterioles. Extraglomerular mesangium lacis cells are located in the angle between the afferent and efferent glomerular arterioles. Granular epithelial peripolar cells are located at the angle of reflection of the parietal to visceral angle of the renal corpuscle.