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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.
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 ...
UVB rays are a primary mutagen that can only penetrate through the epidermal (outermost) layer of the skin and can cause DNA mutations. [4] These mutations arise due to chemical changes within skin cells. These mutations may be clinically related to specific signs of photoaging such as wrinkling. [5] [6] DNA UV mutation
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 ...
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.
The amount and distribution of melanin pigment in the epidermis is the main reason for variation in skin color in Homo sapiens. Melanin is found in the small melanosomes, particles formed in melanocytes from where they are transferred to the surrounding keratinocytes. The size, number, and arrangement of the melanosomes vary between racial ...
Epidermal nevi, neoplasms, and cysts are skin lesions that develop from the epidermal layer of the skin. [8] [26] Aberrant basal cell carcinoma; Acanthoma fissuratum (granuloma fissuratum, spectacle frame acanthoma) Acrospiroma (clear cell hidradenoma, dermal duct tumor, hidroacanthoma simplex, nodular hidradenoma, poroma)