Atlas of plant and animal histology

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Dyes are molecules used to stain the structures of animal and plant tissues, that is, they provide colors to cell structures and extracellular matrix. There are a broad variety of dyes used in histological techniques, and they are selected depending on the sample and the features to be study. Dyes are selected regarding the color they provide, molecular weight, solubility, their affinity to bind and react with tissular molecules.

The structures to be stained and the color the dyes may provide can be guessed from their chemical nature. Regarding the electrical charge, which can be deduced from the molecular composition, dyes are classified into cationic or basic dyes, which stain nuclei and acid carbohydrates, and anionic or basic dyes that stain the cytoplasm and the extracellular matrix. The non-charged dyes can be molecules that stain a variety of structures, liposoluble dyes for staining lipid depots, and mordants that color myelin and nuclei. The size of the dye molecules and their ability to form aggregates is sometimes important because of their difficulty to diffuse through tissues. For example, anionic dyes with different sizes can be selectively used to stain different structures.

Diversity of dyes (modified from Kiernann 2009).

Name Molecule Type Color Staining Procedure
Iodine Inorganic Blue Chromosomes and starch and glycogen depots. Gram bacteria. Protozoa. Lugol's solution
Osmium tetroxide Inorganic Dark grey, bblack It is a histochemical reaction: lipids, proteins, Golgi apparatus, nerves, neurons, glia. Golgi method, Marchi method.
Gold and silver salts Inorganic Impregnations and toning.
Prussian blue Inorganic Blue Cystein and cystin Histochemical method for cystein.
Naphthol green Nitroso Complex
Green Collagen Mixed with anionic dyes.
Picric acid Nitro Anionic Yellow Cytoplasm Thricromic stainings, it is a mordant.
Martius yellow Nitro Anionic Yellow-orange Cytoplasm Together with anionic gyes.
Orange G Azo Anionic Orange Cytoplasm Papanicolaou, Mallory trichrome, Heidenhain trichrome.
Metanil yellow Azo Anionic Yellow Cytoplasm, connective tissue Anionic contrast.
Biebrich scarlet Azo Anionic Scarlet Collagen, basic proteins Masson trichrome (acid fucshin replacement)
Amaranth Azo Anionic Red Cytoplasm, nuclei Gabe thrichrome
Bisckmarck Brown Azo Cationic Brown celular extensions
Janus green B Azo / azine Cationic Green Mitochondria, bacteria
Alcian yellow Azo /thiazole Cationic Yellow / fluorescent Bacteria
Procion brilliant red M2B Azo Reactive Red Vital staining for teeth and bone.
Sudan IV Azo Solvent Red Lipid droplets
Oil red O Azo Solvent Red Lipid droplets
Black Sudan B Azo Solvent
/ Cationin
Black Lipd droplets
Congo red Azo Direct Red Amyloid depots / pH indicator
Benzo blue BB Azo Direct Blue Collagen fibers (birefringense)
Chlorazol black E Azo Direct Black For plants, fungi and microorganisms.
Sirius red F3B Azo Direct Red Collagen fibers (birefringence)
Auramine O Arylmethane Diarylmethane Yellow Tuberculosis bacillus
Pararosanilina Arylmethane Aminotriarylmethane Schiff reagent
Basic fuchsin Arylmethane Aminotriarylmethane Red Nucelus Schiff reagent
Rosaniline Arylmethane Aminotriarylmethane Magenta Non commercial
Magenta II Arylmethane Aminotriarylmethane Magenta NoN coMmercial
Violet crystal Arylmethane Aminotriarylmethane Violet Gram + bacteria
Methyl green Arylmethane Aminotriarylmethane green-blue
Ethyl green Arylmethane Aminotriarylmethane Green-blue Nucleus, DNA, RNA
Acid fuchsin Arylmethane Aminotriarylmethane, anionic Red
Fast green FCF Arylmethane Aminotriarylmethane, anionic Green-blue Connective
Aniline blue (methylen blue) Arylmethane Aminotriarylmethane, anionic Blue Connective
Coomassie brilliant blue Arylmethane Aminotriarylmethane, anionic Blue Proteins in gels
Sodium fluorescein Xanthene Anionic Fluorescent Proteins
Eosin Xanthene Anionic Pink Connetive, cytoplasm
Pyronine Y Xanthene Cationic Red DNA
Rhodamine B Xanthene Cationic Fluorescent
Oregon green Xanthene Cationic Fluorescent
Acriflavine Acridine Cationic Yellow, Fluorescent DNA
Acridine orange Acridine Fluorescent DNA, carbohydrates, vital
Neutral red Azin Cationic Red Nuclei, lysosomes, vacuoles, vital dye
Safranin O Azin Cationic Red plant lignin, nucleus
Azocarmine G y B Azin Anionic Red Cytoplasm
Cresyl violet Oxazin Cationic Violet Nucleus
Gallocyanin Oxazin Cationic Green-blue DNA
Nile blue Oxazin Anionic Blue Vital dye
Orcein Oxazin Cationic Red Elastin, chromosomes
Thionin Thiazin Cationic Blue
Azure A, B y C Thiazin Cationic Blue Blood
Methylen blue Thiazin Cationic Blue
Methylen blue Thiazin Cationic Green-blue Nucleus
Tolouidin blue Thiazin Cationic Blue, metachromatic
Methylene Violet (Bernthsen Thiazin Cationic Blue Blood smears
Calcofluor white Polyene Fluorescent Cellulose
Indigo Carbonyl Anthraquinone
Alzian red Carbonyl Anthraquinone
Nuclear fast red Carbonyl Anthraquinone
Pale Turquoise Sirius blue Phthalocyanine
Alcian blue 86 Phthalocyanine
Cuprolinic blue Phthalocyanine
Luxol fast blue Phthalocyanine
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