Two of the three pictures depict a cuboidal epithelium. As seen in the picture, the cuboidal epithelial cells are cube-like in appearance. Simple cuboidal epithelium can be observed in the kidneys (refer to the 3rd photo), lungs, ovaries, etc. Meanwhile, stratified cuboidal epithelium can be observed in the ducts of salivary glands and male urethra. Cuboidal epithelial cells are known for the following functions: protection, secretion, absorption, and excretion.

For the second picture, we can observe squamous epithelial cells. Squamous epithelial cells are scale-like, flat structures with a nucleus in the center. Simple squamous epithelium lines blood vessels and air sacs. Meanwhile, the stratified squamous epithelium can be found in the body’s epidermis and esophagus. It may or may not contain keratin. This type of epithelium is usually concerned with protection and diffusion of various substances.