Embryology and Anatomy of hair follicles
Each hair follicle is a unique and complex biological system.
The role of hair is primary for the body’s thermal insulation. However, in modern world hair’s function is not only protective, as hair and hairstyle play an important role in people’s social life.
Today, even basic biology research of hair is carried out with the participation of cellular and molecular biology scientists, resulting in new data, which can be utilized in the application of therapeutic methods related to hair growth disorders.
During life in utero, the formation of hair follicles starts from the head and it gradually expands throughout the body. Initially hair follicles produce fluff. Straight after birth, the number of hair follicles remains stable. During the tenth week of gestation hair follicle develops, while in the next developmental stage the initial follicle is formed.
Hair follicles cover all the surface of the skin, excluding the palms, the soles, the glans penis and the labia minora. The total number of hair follicles on human body is around 5 million, while 100,000 are found on the hair of the scalp, having greater density.
Following the formation of vellus hair, which is characteristic of the prenatal period, two types of hair grow:
- a) Telogen hair, which can reach one metre in length. This type of hair has a central medulla, consisting of keratin skeleton. Hair bulb of final anagen hair is located in the subcutaneous fat.
- b) Vellus hair is smaller, it does not contain medulla and their length does not exceed 2 centimetres.