Final answer:
The macula densa cells are cuboidal and columnar, recognizable by their cube shape and central nucleus, playing a crucial role in monitoring sodium ion concentrations in the kidney.
Step-by-step explanation:
The cells of the macula densa are easy to recognize because they are cuboidal and columnar. These cells are part of the distal convoluted tubule (DCT) where they function to sense changes in sodium ion concentration. The cuboidal epithelial cells are cube-shaped with a single, central nucleus, actively involved in secretion and absorption processes.