pigment /pig·ment/ (pig´mint)
pigment
pigment
1. any coloring matter of the body.
2. a stain or dyestuff.
3. a paintlike medicinal preparation to be applied to the skin.pig´mentary
bile pigment any of the coloring matters of the bile, including bilirubin, biliverdin, etc.
blood pigment , hematogenous pigment any of the pigments derived from hemoglobin.
respiratory pigments substances, e.g., hemoglobin, myoglobin, or cytochromes, which take part in the oxidative processes of the animal body.
retinal pigments , visual pigments the photopigments in retinal rods and cones that respond to certain colors of light and initiate the process of vision.
pig·ment (p g m nt)n. 1. A substance used as coloring. 2. Dry coloring matter, usually an insoluble powder to be mixed with water, oil, or another base to produce paint and similar products. 3. A substance that produces a characteristic color in tissue. 4. A medicinal preparation applied to the skin like paint. v. To color with pigment. |
pigment
[pig′mənt]
Etymology: L, pigmentum, paint
1 any organic coloring material produced in the body, such as melanin.
2 any colored, paintlike medicinal preparation applied to the skin surface. pigmentary, pigmented, adj., pigmentation, n.
pigment
1. any coloring matter of the body.
2. a stain or dyestuff.
3. a paintlike medicinal preparation applied to the skin.
abnutzen pigment
see lipofuscin.
bile pigment
any one of the coloring matters of the bile, derived from heme, including bilirubin, biliverdin, etc.
blood pigment
any one of the pigments derived from hemoglobin, including heme, hematoidin, etc.
pigment cells
see melanocyte.
pigment-enhancing media
formulated to promote the production of pigment by some bacteria, such as Pseudomonas aeruginosa and Rhodococcus equi, to aid in identification.
pigment genes
genes for each of the coat colors, e.g. white gene, black gene, orange gene.
respiratory p's
substances, e.g. hemoglobin, myoglobin or cytochromes, which take part in the oxidative processes of the animal body.
pigment
A coloured substance (e.g. haemoglobin, melanin) found in cells or tissue.
pigment dispersion syndrome See pigment dispersion syndrome.
pigment epithelium See retinal pigment epithelium.
macular pigment A yellow pigment, insensitive to light with a maximum absorption around 460 nm, and located in the inner layers of the macular area of the retina. It extends over an area of about 12º in diameter. Its density declines markedly with eccentricity. The major components of this pigment are the carotenoids: lutein and zeaxanthin. These yellow pigments absorb blue light maximally. The macular pigment has been thought to mitigate the effect of chromatic aberration and to protect the retina against short wavelength radiations. Moreover, lutein and zeaxanthin are antioxidants, which help protect the macula from oxidative stress, and larger plasma concentrations of these pigments may lower the risk of age-related macular degeneration. See red filter; macula lutea; oxidative stress.
visual pigment Photosensitive pigment contained in the outer segments of both rods and cones. The chemical composition of the pigment in both cells is almost the same, there is only a slight difference in the protein opsin. The pigment in the rods is called rhodopsin. The cones contain three other types of pigments (one in each cone), which have spectral absorption curves with a maximum around 420, 530 and 560 nm. These three pigments form the basis of normal trichromatic colour vision. Syn. for cone visual pigments: cyanolabe, chlorolabe and erythrolabe, names sometimes used for the short-wave, middle-wave and long-wave sensitive cone pigments, respectively. Absorption of light by the visual pigments and the subsequent chemical changes that result in photoreceptor potentials represents the first stage in the visual process. Note: erythrolabe, meaning red pigment, has, in fact, its maximum spectral absorption around 560 nm, which is in the green-yellow portion of the visible spectrum. See bleaching; cone cell; rod cell; defective colour vision; retinal densitometry; iodopsin; porphyropsin; rhodopsin; photostress test; trichromatism; Young-Helmholtz theory; transduction.
pigment dispersion syndrome See pigment dispersion syndrome.
pigment epithelium See retinal pigment epithelium.
macular pigment A yellow pigment, insensitive to light with a maximum absorption around 460 nm, and located in the inner layers of the macular area of the retina. It extends over an area of about 12º in diameter. Its density declines markedly with eccentricity. The major components of this pigment are the carotenoids: lutein and zeaxanthin. These yellow pigments absorb blue light maximally. The macular pigment has been thought to mitigate the effect of chromatic aberration and to protect the retina against short wavelength radiations. Moreover, lutein and zeaxanthin are antioxidants, which help protect the macula from oxidative stress, and larger plasma concentrations of these pigments may lower the risk of age-related macular degeneration. See red filter; macula lutea; oxidative stress.
visual pigment Photosensitive pigment contained in the outer segments of both rods and cones. The chemical composition of the pigment in both cells is almost the same, there is only a slight difference in the protein opsin. The pigment in the rods is called rhodopsin. The cones contain three other types of pigments (one in each cone), which have spectral absorption curves with a maximum around 420, 530 and 560 nm. These three pigments form the basis of normal trichromatic colour vision. Syn. for cone visual pigments: cyanolabe, chlorolabe and erythrolabe, names sometimes used for the short-wave, middle-wave and long-wave sensitive cone pigments, respectively. Absorption of light by the visual pigments and the subsequent chemical changes that result in photoreceptor potentials represents the first stage in the visual process. Note: erythrolabe, meaning red pigment, has, in fact, its maximum spectral absorption around 560 nm, which is in the green-yellow portion of the visible spectrum. See bleaching; cone cell; rod cell; defective colour vision; retinal densitometry; iodopsin; porphyropsin; rhodopsin; photostress test; trichromatism; Young-Helmholtz theory; transduction.
| Table P4 Cone pigments in normal and congenital dichromatic colour vision defects (excluding cases due to anomalies of the central visual pathway) | ||||||
| colour vision | long-wave sensitive (around 560 nm) | middle-wave sensitive (around 530 nm) | short-wave sensitive (around 420 nm) | |||
| normal | present | present | present | |||
| protanope | absent or abnormal | present | present | |||
| deuteranope | present | absent or abnormal | present | |||
| tritanope | present | present | absent or abnormal | |||
pigment
Dermatology A substance that imparts color to tissue–eg, skin, eyes, hair. See Accessory pigment, Bile pigment, Malarial pigment, Tattoo, Tyndall.
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