The outer root sheath (ORS) of hair follicles is a multilayered tissue made up predominantly by undifferentiated keratinocytes (it1 , it2 ) Although the functions of the ORS cells for hair growth are not established, it is known that the ORS cells can contribute to the regeneration of the epidermis, as during healing of superficial wounds where the ORS cells migrate out of the follicle to repopulate the denuded area (3 , 4 ). Recent studies also suggest that stem cells for various epithelial cell populations of the skin are located in the ORS tissue (5 , 6
