Mouse skin was treated with an enzyme to remove a sheet of cells containing the upper layers of skin (epidermis), together with attached hair follicles, from the deeper portions of skin (the dermis).  This intact sheet of epidermis was then stained with a dye to visualize hair follicles, which appear purple in this image. In the center of each follicle, a hair shaft is visible. Scientists are studying hair follicles intensely because they contain stem cells that might be important in basal cell carcinoma.