The skin is the body’s largest organ, weighing close to 3 kilograms. Skin is a complex structure which broadly has 2 components, the epidermis, which is the more superficial structure, and the best barrier to environment the nature has produced, and the dermis, which maintains the structure of the skin, due to presence of collagen, and elastin fibers, blood vessels, nerve fibres, sweat and sebaceous glands. The outermost layer of the epidermis, the ‘horny layer’ is made up of dead keratin cells, and absorbs UVB.
It is the basal layer of epidermis that contains melanocytes in varying densities, more in blacks and lesser in whites. Melanocyte distribution and its role Melanocytes, are cells of neural origin, and migrate to the epidermis from their area of origin, primarily functions to produce a pigment, melanin, which absorbs radiant energy from the sun and protects the skin from the harmful effects of ultraviolet radiation. Melanin accumulates in highly organized microstructures known as melanosomes which are in close proximity to the keratinocytes in the epidermis.
Melanocytes are found in the basal layer of the epidermis as well as in hair follicles, the retina, uveal tract, and leptomeninges ( Revis, 2006). Thus these are the sites where melanoma is commonly found Melanosomes are found in high density in regions of the body which are highly exposed to sun light, and in skins of people in the tropics. Absolute numbers of melanosomes are the same among the sexes and various races. Differing pigmentation among individuals is related to melanosome size rather than cell number.