Skin Health How Melanocytes Defend Your Skin Against UV Rays By Heather L. Brannon, MD Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. Learn about our editorial process Updated on July 02, 2022 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Casey Gallagher, MD Medically reviewed by Casey Gallagher, MD Casey Gallagher, MD, is board-certified in dermatology and works as a practicing dermatologist and clinical professor. Learn about our Medical Expert Board Fact checked Verywell Health content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication. Learn more. by Nick Blackmer Fact checked by Nick Blackmer LinkedIn Nick Blackmer is a librarian, fact-checker, and researcher with more than 20 years’ experience in consumer-oriented health and wellness content. Learn about our editorial process Print A melanocyte is a type of cell that's primarily located in the basal layer of the epidermis. Melanocytes produce melanin, a brown pigment that is responsible for skin coloration and protecting against the harmful effects of UV light. Melanocytes are also present in the hair and in the irises of the eyes. Ed Reschke / Photolibrary / Getty Images The Makeup of Melanocytes Melanocytes develop in the neural crest: a temporary group of embryonic cells that gets pinched off as the neural tube—or the pre-spinal cord—forms. During the embryonic stage of life, melanocytes move from the neural crest to the basal layer of the epidermis. Melanocytes are branch-shaped, which allows them to transfer melanin to other skin cells, like keratinocytes. Keratinocytes are the most common skin cells that strengthen the hair, nails, and skin. Production Melanocytes produce melanin, which gets deposited into the epidermal cells. There are two different types of melanin that melanocytes produce: eumelanin, which is dark brown in color, and pheomelanin, which can have a red or yellow tint. Melanin production is regulated by a peptide hormone that's located in the pituitary gland and known as the melanocyte-stimulating hormone. Pituitary tumors and spiked estrogen levels that occur during pregnancy cause the pituitary gland to produce more of this hormone. But melanocytes don't always function as they should. Vitiligo, for example, is a skin condition in which the immune system attacks melanocytes. The melanocytes cease producing melanin, resulting in white, oval-shaped patches of skin that gradually grow larger. The lack of melanin also turns the hair in the affected area(s) white. Other conditions that are affected by a lack of melanin include albinism and phenylketonuria. The Importance of Melanin The color of human skin varies. Its exact shade is determined by the blood that flows through it, diet, and the melanin produced by melanocytes. Humans generally have the same amount of melanocytes; the amount of melanin that those melanocytes produce, however, is what varies. Melanin protects the skin by shielding it from the sun. When the skin is exposed to the sun, melanin production increases, which is what produces a tan. It's the body's natural defense mechanism against sunburn. Time in the Sun Comes With a Cost Everyone looks better with a glow, but it comes at a cost. Spending extended amounts of time in the sun (or in a tanning bed) is dangerous. Take a sunburn, for example. It takes time for melanocytes to produce melanin and protect the skin from the sun's harmful rays. When melanocytes can't work quickly enough to create a tan, the UV rays from the sun can burn the skin and leave it looking pink or bright red. Sun damage also accumulates over time, which can lead to skin cancer. The lighter your skin, the greater your risk of developing skin cancer. So make sure that you see a dermatologist regularly for a skin exam. Direct sunlight isn't all bad, however. The skin uses sunlight to make vitamin D, which absorbs calcium and is essential for bone strength and growth. 6 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. MedlinePlus. MC1R gene. Wang JX, Fukunaga-Kalabis M, Herlyn M. Crosstalk in skin: melanocytes, keratinocytes, stem cells, and melanoma. J Cell Commun Signal. 2016;10(3):191-196. doi:10.1007/s12079-016-0349-3 Endocrine Society. Melanocyte-stimulating hormone (MSH). MedlinePlus. Vitiligo. Yamaguchi Y, Hearing VJ. Melanocytes and their diseases. Cold Spring Harb Perspect Med. 2014;4(5):a017046-a017046. doi:10.1101/cshperspect.a017046 Solano F. Photoprotection and skin pigmentation: melanin-related molecules and some other new agents obtained from natural sources. Molecules. 2020;25(7):1537. doi:10.3390/molecules25071537 By Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit