juxtaglomerular apparatus juxtaglomerular apparatus the juxtaglomerular apparatus (also known as the juxtaglomerular complex) is a structure in the kidney that regulates the function of each nephron, the functional units of the kidney. the juxtaglomerular apparatus is named because it is next to (juxta-) the glomerulus. juxtaglomerular apparatusa renal corpuscle, showing the juxtaglomerular apparatus with juxtaglomerular cells (granular cells), macula densa cells and, extraglomerular mesangium.identifiersmeshd007606fma83599anatomical terminology the juxtaglomerular apparatus consists of three types of cells: the macula densa, a part of the distal convoluted tubule of the same nephron juxtaglomerular cells, (also known as granular cells) which secrete renin extraglomerular mesangial cells location the juxtaglomerular apparatus is part of the kidney nephron, next to the glomerulus. it is found between afferent arteriole and the distal convoluted tubule of the same nephron. this location is critical to its function in regulating renal blood flow and glomerular filtration rate. function juxtaglomerular cells the renin–angiotensin system. it is activated when juxtaglomerular cells are poorly perfused.