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Scanning electron micrograph (SEM) of damaged human head hair, with tiny split ends along the shaft. Hair is a fibrous protein (keratin), which develops out of a tubular hair follicle in the epidermis of the skin. The shaft, seen here, 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 145 at 35mm size, X 1000 at 8x10-inch size.
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