Fig. 1

Normal human scalp hair follicle structure. a A hair follicle microdissected from human scalp (an anagen hair follicle is presented). b Corresponding histopathology image. The bulge area harbors stem cells. Hair matrix cell proliferation in the bulb results in hair shaft elongation. c Hair follicle epithelial stem cells locate in the outermost layer of the outer root sheath. d The dermal papilla (DP) and the dermal sheath (DS) are mesenchymal components demonstrate trichogenic activity