Simple cuboidal tissue is found in which structures?

• A. Lining of blood vessels
• B. Digestive tract lining
• C. Kidney tubules and thyroid gland
• D. Skin epidermis

Answer: (C)

Simple cuboidal epithelium is a single layer of cube-shaped cells that is well suited for secretion and absorption. In the kidneys, the tubules are lined by this type of epithelium to actively reabsorb water, ions, and nutrients from the filtrate, with microvilli in places to increase surface area for uptake. In the thyroid gland, the follicles are surrounded by simple cuboidal cells that synthesize and secrete thyroid hormones into the colloid and onward to the bloodstream. Lining of blood vessels is made of simple squamous endothelium, which is a flat, thin single layer, not cuboidal; the digestive tract is lined by simple columnar epithelium specialized for absorption and secretion; and the skin epidermis is stratified squamous, offering protection. Therefore, structures that feature simple cuboidal epithelium include kidney tubules and the thyroid gland.