Humans have approximately five million hair follicles, which offer protection from cold and UV radiation, produce sebum, and can have a significant psychological impact when growth or structure is unbalanced.
The beginning of hair growth is made by cells which are the hair follicle cells.
Hair follicle cells divide approximately only 25 times throughout a lifetime before experiencing deteriorating with age, which is only half of normal somatic cells life cycle.
Like skin, hair forms by rapid division and differentiation of stem cells, forming keratinocytes that migrate, flatten, and die, forming keratinized cells. The final hair product exposed on the skin's surface will be composed entirely of keratin (a protein). The growth of the hair follicle is cyclical. Stages of rapid growth and elongation of the hair shaft alternate with periods of inactivity and regression driven by cell death signals. This cycle can be divided into three phases: anagen (growth), catagen (transition), and telogen (rest).
Each hair cycle lasts for three months
Exosomes promotes the anlagen phase of the hair cycle and shortens the telegenic phase.