Epithelial cells can undergo specialization to become gland cells, which secrete substances at the epithelial surface.

Cuboidal epithelium provides mechanical support in structures such as kidney tubules and salivary gland ducts.

Cuboidal epithelium is found lining kidney tubules and ducts of salivary glands.

Cilia in ciliated columnar epithelium move rhythmically to push mucus forward, aiding in the clearance of debris and pathogens from the respiratory tract.

Ciliated columnar epithelium, found in the respiratory tract, has cilia—hair-like projections on the cell surface—that can move and help clear mucus.