Artificial hair integrations is a type of synthetic fiber that can withstand heat up to 400 °F (200 °C), and can actually outlast human hair. It is very similar to human hair given it is tangle-free and has a natural sheen. It can be straightened or curled, however, it takes longer to set and futura cannot be colored. It is sometimes sold as a human hair blend. The human hair shaft is made up of dead, hard protein, called keratin, in three layers. The inner layer is called the medulla and may not be present. The next layer is the cortex and the
Leg hair of the hormone testosterone in males that most females have a lower level of. Fibroblast growth factor 5 (FGF5) is a secreted signaling protein. The expression of this protein is detected in hair follicles from the mice that scientists have experimented on. The hair follicles are localized to the outer root sheath during one of the phases of the hair growth cycle. Such experiments conclude that the protein FGF5 functions as an inhibitor when pertaining to hair elongation. Seasonal changes are also known to affect hair growth. For instance, one experiment had concluded that the rate of hair growth for