MICHAEL ABBEY / SCIENCE PHOTO LIBRARY MICHAEL ABBEY / SCIENCE PHOTO LIBRARY
Light micrograph of human scalp (longitudinal section) showing a single hair follicle. The follicle is tubular, consisting of 5 layers of epithelial cells, which merge at the bulb (lower left). As the hair is pushed towards the skin surface, the inner 3 layers form the hair shaft, while the outer 2 form the epithelial sheath. The innermost 2 layers of medulla & cortex (red) are keratinized (forming bulk of hair) & are surrounded by a thin cuticle. The 4th & 5th layers are the root sheaths. The outer layer (pale pink) is surrounded by connective tissue. The white, regular cells constitute the hypodermis. Magnification: x34 at 35mm size.
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