The simple cuboidal epithelium is made of a single layer of cuboidal epithelial cells. The simple columnar epithelium is made of a single layer of prismatic cells. The simple cuboidal epithelium can be found, for example, in the renal tubules and in the walls of the thyroid follicles. The simple columnar is the epithelium that covers internally the intestines, the stomach and the gallbladder, for example.