nonciliated

Nonciliated refers to cells or tissues that lack cilia on their apical surface. Cilia are slender, often motile projections that help move fluids or mucus; their absence is a characteristic used in tissue classification and histology.

Nonciliated epithelia occur in a variety of organs and serve different functions. In many glands and ducts, including parts of the salivary and pancreatic duct systems, the lining is nonciliated and adapted for secretion or passage of fluids. The absorptive surfaces of the small intestine and certain nephron segments in the kidney are also nonciliated; these tissues often rely on microvilli instead of cilia to increase surface area. The urinary tract lining is typically nonciliated as well, with transitional (urothelial) epithelium forming the bladder, ureters, and part of the urethra.

Function and structure differ from ciliated epithelia. Nonciliated cells generally do not possess the coordinated mucus-clearing mechanism provided by motile cilia. Instead, they may specialize in absorption, secretion, or barrier protection. Microvilli, tight junctions, and other apical–basal features support their specific roles in transport, digestion, or containment of luminal contents.

In practice, tissues can present mixtures of ciliated and nonciliated cells depending on location and function. The term nonciliated is used descriptively to distinguish these cells from adjacent ciliated epithelia, such as many cells lining the respiratory tract.