10 Oct Embryology of Hair
Hair formation, hair follicle development is an excellent example of two distinct developmental processes: epithelial-mesenchymal interactions and pattern formation.
The differentiated hair follicle contains 20 or more different cell types. Melanocytes, which are responsible for hair color is neural crest origin, and with aging, their numbers decrease leading to the whitening of the hair.
Hair follicle development begins as an epithelial-mesenchymal interaction between weeks 9 – 12. Lanugo hair is replaced in the late fetal or early neonate by value and terminal hairs. Under the influence of steroidal hormones, the second round of development occurs during puberty.