#pigment

• Acanthosis — A histopathological alteration consisting of the thickening of the prickle cell layer (stratum spinosum) of the epidermis, caused by the proliferation of malpighian cells. In a clinical macroscopic sense, the term is frequently associated with 'Acanthosis nigricans', a skin condition characterized by hyperpigmented, velvety, and rough plaques, predominantly localized in intertriginous areas (neck, axillae, groin), serving as an important cutaneous marker for insulin resistance, obesity, or endocrine disorders.
• Acrochroic — Regarding spores or mycological cellular structures; exhibiting intense pigmentation localized exclusively at the apex, tip, or terminal extremity, while the rest of the membrane remains translucent.
• Achromatism — The property of an optical system to transmit or reflect light without producing chromatic aberrations, allowing the formation of a sharp image without fringing. In a medical or biological context, the term refers to the total absence of colored pigments in a tissue or anatomical structure, or a visual anomaly where the subject perceives the world exclusively in shades of white, black, and gray.
• Achromatosis — A generalized pathological condition characterized by the total absence or severe diminution of normal pigmentation within a tissue, organ, or the entire organism. In dermatology, the term describes severe states of cutaneous depigmentation (such as extreme forms of albinism or vitiligo universalis) where cells no longer produce melanin.
• Achromaturia — A pathological clinical condition manifested by the emission of completely colorless or pale urine, lacking normal urinary pigments (such as urochrome and urobilin). This phenomenon may indicate extreme dilution in diabetes insipidus, a severe inability of the kidneys to concentrate urine in advanced renal failure, or a massive and sudden intake of fluids.
• Achromasia — A general term designating the total absence of color or pigments within a structural medium. In medicine, it is synonymous with achromatopsia (total color blindness) or describes cellular and cutaneous depigmentation (lack of melanin); in optics, it defines the perfect correction of chromatic aberrations in a lens system.
• Achromic — Lacking color, discolored, or completely devoid of natural pigments; describing a cellular structure, plant tissue, or microscopic organism presenting a native transparency or chromatic neutrality.
• Achromia — The total congenital or acquired absence of normal pigmentation of the skin, hair, or other tissues, caused by the lack or destruction of melanocytes and melanin production. This general medical term covers manifestations such as generalized albinism or completely white patches occurring in advanced vitiligo.
• Leukoderma — A congenital or acquired cutaneous pathological condition characterized by the total absence or severe and extensive diminution of normal skin pigmentation, manifesting as broad white patches or generalized depigmentation of the epidermis. This structural disorder is caused by the absence, destruction, or chronic metabolic dysfunction of melanocytes, leading to a complete halt in melanin production and resulting in extreme skin sensitivity to ultraviolet radiation.
• Watercolor — A painting technique based on the use of special paints whose pigments are diluted exclusively in water, applied on porous supports, usually thick paper or cardboard; also, it designates the artwork created through this process or the solid cake of colored pigment. This structural style stands out for its transparency, fluidity, delicate overlapping of shades, and a specific luminosity due to the white of the paper remaining partially visible.
• Adipochrome — A natural lipid or carotenoid pigment, fat-soluble, historically isolated from the adipose tissue of certain animals or insects, responsible for the yellow or orange coloration of fat stores. This biochemical structure serves as a metabolic indicator and reflects the accumulation of certain metabolites or exogenous compounds in fat cell vacuoles.
• Albino — A person, animal, or plant affected by albinism; characterized by the total or partial congenital absence of melanin pigment from the skin, hair, and eyes, resulting in a white or very light coloration and pink or pale blue irises.
• Albinism — A congenital anomaly characterized by the total or partial absence of melanin pigment in the skin, hair, and eyes, causing a whitish appearance of the body and extreme sensitivity to solar radiation.
• Albino — An invariable form or informal adjective, used as a modern variant or direct loanword for albino; an individual, animal, or organism affected by albinism, characterized by the congenital absence of melanin pigment, having completely white skin, hair, or fur and eyes with pinkish or light-blue reflections.
• Albinoidism — A softened or partial form of albinism, characterized by a discrete, congenital, and generalized reduction of melanin pigment, without reaching the total depigmentation specific to classic albinism; a structural condition resulting in an unusually light shade of skin, hair, and irises.
• Albinism condition — The state, quality, or condition of being albino; the evident presence of albinism manifestations within a living organism; an abstract term sometimes used as a rare synonym in old scientific literature to describe the depigmentation anomaly.
• Allochlorophyll — An isomeric form of chlorophyll, obtained artificially or arising through minor chemical and structural alteration of the natural green pigment in plant or algal cells. This organic compound retains its basic properties in capturing the light spectrum, but exhibits modifications in the molecular structure of the porphyrin ring, being studied in plant physiology laboratories to understand the stability of the photosynthesis process.
• Alizari — A rare technical or commercial term used to designate the root of the Rubia tinctorum plant (madder), from which a natural red pigment is extracted, or the historical name given to the coloring substance obtained directly from this plant before the advent of synthetic variations.
• Alizarin — A solid organic substance, crystallized in red-orange needles, insoluble in water, initially extracted from the madder root (Rubia tinctorum) and later obtained synthetically from anthracene. It is widely used in the textile industry as a highly stable dye for coloring in intense shades of red, purple, or black, as well as in medicine or microscopy as a chemical indicator.
• The hazelnuts — The definite articulated form of the plural noun 'alune' (hazelnuts). In everyday speech and popular medical terminology, it functions as the plural form for 'aluniță' (melanocytic nevi), designating small pigmented spots or benign growths on the skin.