SCIENCE PHOTO LIBRARY. SCIENCE PHOTO LIBRARY.
Scanning electron micrograph (SEM) of a human head hair, showing a normal shaft with a flake of dandruff. Hair is a fibrous protein (keratin), which develops out of a tubular hair follicle in the epidermis of the skin. The shaft, the part visible, consists of three layers: an outer layer or cuticle, which is scaly in normal hair but has been lost in this specimen. Beneath is the cortex containing hair colour pigments. The medulla forms the central core, which may be hollow. Hair cells are dead except for a layer at the base of the root where they divide to form new cells, pushing the older ones upward. Magnification: X 165 at 35mm size, X 1150 at 8x10-inch size.
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