Hair follicle formation and development normally takes place during fetal development. However, after a wound hair follicle formation and regeneration can still occur in mouse and rabbits (Ito et al., 2007). The way the skin responds to a wound differs between mammals. Humans for example respond to deep skin wound by blocking the hair formation and instead it forms a scar (Reynolds et al., 1999). On the other hand, rodents regenerate their hair after a wound (Ito et al., 2007).
These differences between mammals are due to different concentration of some growth factors that are found in the skin (Gay et al., 2013). Gay and his colleagues showed that dermal layer contains γδ T cells that secret growth factor 9. These growth factors enhance hair follicle regeneration after a wound (Gay et al., 2013). They showed that reducing factor 9 expression decreases the hair regeneration during wound healing (Gay et al., 2013). By contrast, over expression of factor 9 increases the hair follicle regeneration during wound healing (Gay et al., 2013). Based on the results, they concluded that growth factor 9 enhance Wnt activation that induces hair regeneration after a wound (Gay et al., 2013). …show more content…
They opened the mice and leave the wound to heal. During the healing they exposed the animal to different Wnt activity (Ito et al., 2007). They showed that blocking the pathway of Wnt activity in the skin during healing leads to decrease in the number of new hair follicle (Ito et al., 2007). On the other hand, increasing the activity of Wnt in the mice skin increases the number of new hair follicles (Ito et al.,