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Alfred Blaschko, a private practice dermatologist from Berlin, first described and drew the patterns of the lines of Blaschko in 1901. He obtained his data by studying over 140 patients with various nevoid and acquired skin diseases and transposed the visible patterns the diseases followed onto dolls and statues, then compiled the patterns onto a composite schematic of the human body.
This then attracts neutrophils which lead to an increase in oxidative damage through the generation of free radicals. [ citation needed ] Additionally, UV radiation would cause the down-regulation of an angiogenesis inhibitor, thrombospondin-1, and the up-regulation of an angiogenesis activator which is platelet -derived endothelial cell growth ...
Human skin pigmentation varies substantially between populations; this has led to the classification of people(s) on the basis of skin colour. [ 3 ] In terms of surface area, the skin is the second largest organ in the human body (the inside of the small intestine is 15 to 20 times larger).
Total melanin content in the epidermis ranges from around 0 μg/mg in albino epidermal tissue [8] to >10 μg/mg in darker tissue. [9] In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Eumelanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV ...
Melanin is a dark pigment primarily responsible for skin color. Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones.
They range in color from light brown [5] to red or black and are located in areas most often exposed to the sun, particularly the hands, face, shoulders, arms and forehead, and the scalp if bald. The spots derive their name from the fact that they were once incorrectly believed to be caused by liver problems, but they are physiologically ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 11 February 2025. "Skin pigmentation" redirects here. For animal skin pigmentation, see Biological pigment. Extended Coloured family from South Africa showing some spectrum of human skin coloration Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among ...
Freckles are clusters of concentrated melaninized cells which are most easily visible on people with a fair complexion.Freckles do not have an increased number of the melanin-producing cells, or melanocytes, but instead have melanocytes that overproduce melanin granules (melanosomes) changing the coloration of the outer skin cells (keratinocytes).