Which epithelial type lines ducts of glands and kidney tubules, offering a passageway with or without the ability to absorb and secrete?

• A. Simple squamous
• B. Simple columnar
• C. Simple cuboidal
• D. Pseudostratified epithelium

Answer: (C)

The tissue type lining ducts of glands and kidney tubules is simple cuboidal epithelium. It consists of a single layer of cube-shaped cells whose height and width are about equal, with central round nuclei. This arrangement provides enough cytoplasm and organelles to support active secretion and absorption, which are essential functions in glandular ducts and renal tubules. In glands, this epithelium forms the walls of ducts through which secretions pass; in kidney tubules, it lines the passageways where reabsorption and secretion occur to modify the filtrate.

In contrast, simple squamous epithelium is a thin diffusion barrier found where rapid exchange is needed, such as in alveoli and lining vessels. Simple columnar epithelium is taller and typically specialized for robust absorptive and secretory activity in the digestive tract, often with microvilli. Pseudostratified epithelium appears layered but all cells touch the basement membrane and is common in the respiratory tract and portions of the male reproductive system, not typically in glandular ducts or kidney tubules.