Origin and distribution Melanin is the black or brown pigment that is responsible for the color of the skin, hair, and local variation in pigmentation. It is produced only by the melanocytes. Melanocytes derive embry-ologically from melanoblasts. They migrate from the inner neural crest to the dermoepidermal junction. Mature melanocytes are essentially confined to the basal layers of the epidermis. In dark-skinned ethnic groups, pigment activity can be observed from the fourth fetal month.
The color of the skin depends on both the amount and distribution of the melanin in the epidermis (and occasionally in the dermis) and the vascularization of the skin. Additional factors that influence the skin color include hormones, such as melanocyte-stimulating hormone and the sex steroids, and exogenous factors, such as heat, injury, and exposure to ultraviolet light. Skin color can range from pale-yellow to gray-black. There are characteristic regional variations in skin color common to all ethnic groups, (e. g., palms are lighter than the rest of the hands, while around the eyes skin color is usually darker) as well as specific ethnic differences, such as pigment-free mucous membranes in Europeans.
Describing Skin Color In describing skin color, it is essential to name the body area of observation (ventral, dorsal, chest, palms, etc.). Usually the skin is lighter on the ventral part of the body compared to the dorsum. In addition, the appearance of areas exposed to the sun versus protected areas should be described, as well as the differences between them. A skin color table may be helpful for special situations (see Bibliography).
Remarks For documentation of skin color, a color photograph is useful. The color of tooth enamel, nails, iris, body, and scalp hair, as well as skin, should be recorded. The skin around the nipple, especially after pregnancy, may be darker due to hormonal influences. Genital skin and areas of apocrine sweating are usually darker. Pigment changes can occur in specific diseases, such as Addison disease (a bronze skin color) or albinism (where the skin and hair pigment may be reduced or absent).
Pitfalls Skin color can be artificially altered and pigmented by make-up, dirt, and different forms of tattooing. Artificial light may give unusual tones or hues to the natural colors.
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