Follikelhår

Follikelhår, also known as vellus hair, is the short, fine, and usually unpigmented hair that covers most of the body. This type of hair is distinct from terminal hair, which is thicker, darker, and more prominent, typically found on the scalp, eyebrows, and pubic areas. Follikelhår develops during fetal development and is present at birth. It plays a role in thermoregulation by trapping a layer of air close to the skin.

The growth cycle of follikelhår is shorter than that of terminal hair and involves three main phases: anagen (growth), catagen (transition), and telogen (resting). Unlike terminal hair, follikelhår is not significantly influenced by androgens, the male sex hormones, which is why it remains fine and light even in adults. However, hormonal changes, such as those during puberty, can lead to the transformation of some follikelhår into terminal hair in specific areas.

The density and distribution of follikelhår can vary between individuals and are influenced by genetics. In some cases, excessive growth of fine, dark hair can occur, a condition known as hypertrichosis, which may involve follikelhår or terminal hair. Conversely, conditions like alopecia can affect hair growth, including follikelhår, though it is less commonly the primary focus of hair loss discussions compared to terminal hair. Understanding the nature of follikelhår is important in dermatology and trichology for diagnosing and managing various hair-related conditions.