1. The epidermal melanin unit. A
The epidermal melanin unit. A. Representation showing the relationship between basal melanocytes, keratinocytes, and Langerhans cells, shown at the upper layer of the epidermis. (From Quevedo WC Jr.: The control of color in mammals. Am Zoology 9:531, 1969, with permission.) B. Electron micrograph of the dermal–epidermal junction of human skin showing a dendritic melanocyte (M) among the basal keratinocytes (K). k′ represents a basal keratinocyte undergoing mitosis with condensed chromatin (arrows). (Bar = 10.0 μm.) (Illustration used with permission from Raymond E. Boissy, Department of Dermatology, University of Cincinnati, Cincinnati, Ohio.) C. Human epidermis immunostained for fibroblast growth factor-2 (FGF2). The figure shows basal keratinocytes with peroxidase reaction indicating the presence of immunore-active FGF2. Arrows point to melanocytes. (Used with permission from Glynis Scott, MD, Department of Dermatology, University of Rochester School of Medicine and Dentistry, Rochester, NY.) D and E. Distribution of melanosomes within keratinocytes in lightly pigmented Caucasian and darkly pigmented African-American skin. Melanosomes in lightly pigmented Caucasian skin (D) are distributed in membrane-bound clusters. In contrast, in darkly pigmented African-American skin (E) the melanosomes are individually distributed throughout the cytoplasm of epidermal keratinocytes. Melanosomes in both skin types are frequently concentrated over the apical pole of the nucleus (arrows). L = Langerhans cell. (Bar = 3.0 μm.) (Used with permission from Minwalla L et al: Keratinocytes play a role in regulating distribution patterns of recipient melanosomes in vitro. J Invest Dermatol 117:341, 2001.)
Source: Chapter 72. Biology of Melanocytes, Fitzpatrick's Dermatology in General Medicine, 8e
Citation: Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, Wolff K. Fitzpatrick's Dermatology in General Medicine, 8e; 2012 Available at: Accessed: November 12, 2017
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