Melanocyte biology and disorders of pigmentation
How melanocytes make and transfer melanin, the POMC and MC1R pathway that links ACTH to Addison pigmentation, tanning after UVA and UVB, why skin types differ, and how to reason through hypopigmentation, depigmentation and hyperpigmentation, including drug causes and the pharmacology of depigmenting agents.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Melanocytes come from the neural crest and sit in the basal epidermis, roughly 1 for every 10 basal keratinocytes. Each one supplies melanin to about 36 keratinocytes: the epidermal melanin unit.
- Melanin is made inside melanosomes, transferred along dendrites to keratinocytes, and parked as a cap over the nucleus to absorb UV before it reaches DNA.
- Skin colour depends on what melanocytes make and how they package it, not on how many there are.
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Sources
- Melanocyte biology and skin pigmentationLin JY, Fisher DE, Nature 2007;445:843-50, 2007
- Vitiligo: mechanisms of pathogenesis and treatmentFrisoli ML, Essien K, Harris JE, Annu Rev Immunol 2020;38:621-48, 2020
- Rook's Textbook of Dermatology (10th ed.)Wiley-Blackwell (Griffiths, Barker, Bleiker, Hussain, Simpson, eds), 2024
- Dermatology (5th ed.)Elsevier (Bolognia, Schaffer, Cerroni, eds), 2024
- Therapeutic Guidelines: DermatologyAU/NZTherapeutic Guidelines Limited, 2026
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback