folikul

Folikul is a term used in several languages to denote a small sac or cavity within tissue, often surrounding, containing, or supporting a developing element. The word derives from Latin folliculus, meaning a little bag or pouch, and in medical and biological usage it commonly refers to structures such as a hair follicle or an ovarian follicle.

In humans and other mammals, the most familiar folikuli are hair follicles. A hair folikul is a dynamic organ located in the skin, consisting of a hair bulb at its base, a surrounding dermal papilla and matrix cells, and connections to sebaceous glands and arrector pili muscles. Hair growth proceeds through cycles called anagen (growth), catagen (regression), and telogen (rest). Inflammation of hair follicles, known as folliculitis, can result from infection, irritation, or other skin conditions and is usually treated with proper hygiene and, when needed, antimicrobial therapy.

Ovarian folikuli are another well-known type, consisting of fluid-filled sacs that house developing oocytes. They progress through stages—from primordial to primary, secondary, and antral (Graafian) follicles—while secreting hormones such as estrogen. The maturation of a dominant follicle leads to ovulation and release of the oocyte, enabling reproduction.

In botany, a folikul (often called a follicle in English) is a dry fruit that splits open along a single seam to release seeds, as seen in milkweed and foxglove. The term folikul is therefore used in different contexts to denote distinct structures that share a common idea of a small, enclosing unit.

See also: hair follicle, ovarian follicle, plant follicle.