And these cells found within close proximity are shown in purple. So we essentially have our a fearing arterial running along this location and it empties out into the glomerulus which is located right here. And these purple cells are known as the maculodeensa. Now recall that the maculodeensa are part of the juxtaglomeral apparatus, the structure found in the nephron that regulates and controls the functionality of the nephron. So the question is what exactly is the purpose of these purple cells, the macular densa cells? Well, they serve two important functions.