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The test compares the cytotoxic effect of a test substance when tested after the exposure, then tested in the absence of exposure to a non-cytotoxic dose of UVA/vis light. Cytotoxicity is expressed as a concentration-dependent reduction of the uptake of the vital dye - Neutral Red .
Hyperpigmentation can be diffuse or focal, affecting such areas as the face and the back of the hands. Melanin is produced by melanocytes at the lower layer of the epidermis . Melanin is a class of pigment responsible for producing color in the body in places such as the eyes, skin, and hair.
They have a dominant gene that causes hyperpigmentation (Fibromelanosis), making the chicken entirely black; including feathers, beak, and internal organs. Melanism in feral rock doves are actually quite common,to some extent, especially if the area is abundant with the species. The amount of pigmentation is varied, from a slight darker ...
Melasma (also known as chloasma faciei, [1]: 854 or the mask of pregnancy [2] when present in pregnant women) is a tan or dark skin discoloration.Melasma is thought to be caused by sun exposure, genetic predisposition, hormone changes, and skin irritation. [3]
Postinflammatory hyperpigmentation (PIH) is a skin condition characterized by the darkening of the skin (hyperpigmentation) following an inflammatory injury, such as acne, dermatitis, infectious disease, or trauma. Less frequently, it may occur as a complication of a medical procedure performed on the skin. It is a common cause of skin ...
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).
Tyrosinase family related genes plays an important role in the evolution, genetics, and developmental biology of pigment cells, as well as to approach human disorders associated with defects in their synthesis, regulation or function in vertebrates three types of melanin producing pigment cells are well known since embryonic origin i.e., from ...
Hemosiderin hyperpigmentation is pigmentation due to deposits of hemosiderin, and occurs in purpura, haemochromatosis, hemorrhagic diseases, and stasis dermatitis.