Diseases of Cutaneous Appendages

Anagen Phase

Catagen Phase

Telogen Phase

Hair basics

Hair follicle formation:

  • Nine weeks’ gestation, follicles seen

  • By 18th week, hair on entire body (except palms/soles/genitalia)

  • Growth rate = 1 mm every 3 days (or 0.35–0.37 mm/day), or 1 cm per month

  • Lose an average of 50–100 hairs per day

Pigment predominantly in cortex layer:

  • Eumelanin = brown/black hair

  • Pheomelanin = red/blonde hair: red hair often has variant to MC1R gene (melanocortin receptor)

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