ABSTRACT
Hair, scales, feathers, claws, horns, and nails are all derived from skin and so all consist of keratinized modi ed epidermal cells [1]. Hair and nails are of major interest to dermatologists, to toxicologists, and to those interested in forensic and medicolegal investigations. The slower growth of nails (toenail, 0.05 mm/day: nger nail, 0.1 mm/day) compared with human scalp hair bers (around 0.35 mm/day), and the fact that nails (especially of the foot) are not normally exposed to external contaminants, make the nail particularly useful for retrospective analysis [2].
