Ühekihilised

Ühekihilised is a term used in Estonian biology to describe structures that consist of a single cell layer. The adjective is formed from the components üks (one) and kiht (layer), with the common Estonian suffix -iline/-ilised to indicate an adjective describing a grouping. In scientific texts it is used to characterize tissues, membranes, or coverings that are arranged in a single layer, in contrast to multilayered structures described as mitmekihilised.

The most common context for the term is histology, where ühekihiline epiteel refers to simple epithelium—tissues built from a single layer of cells. Subtypes are typically defined by cell shape, such as squamous, cuboidal, or columnar, though the classification remains primarily descriptive. The concept also appears in botany to describe plant epidermis or other coverings that consist of one cell layer, and in materials science to discuss monolayer films or coatings.

In usage, ühekihilised describes structures that are flatly arranged in one layer, contrasting with layered or stratified forms. For example, many mucosal surfaces are lined by simple epithelium to facilitate diffusion or secretion, whereas skin is multilayered. The term is most common in formal or academic contexts and is less frequent in everyday language.

See also: mitmekihilised, epiteel, epidermis, monolayer.