Staining

process of applying dyes on the sections to see and study the architectural pattern of the tissue and physical characteristics of the cells

Cationic (basic) dye stains

acidic structures

anionic (acid) dye stains

basic structures

Forms a complex with a dye ; complex is large and is “trapped” within the tissue or organism and is not readily released during
differentiation

complexes with crystal violet during gram staining

Does not participate in the staining reaction ; increasing the intensity, crispness and selectivity of the dye ; Not essential for the chemical union of the dye with the tissue

accentuator in carbolfuchsin and carbolthionine

accentuator in in gentian violet

accentuator in Loeffler’s methylene blue

Used in metallic impregnation techniques for the demonstration of CNS tissue component ; Also acts as accentuators and they often consists of hypnotic drugs

examples of accelerators

when added to the dye will slightly alter the color of a dye ; Differ from the chromotrope in that they are exogenous by nature

examples of modifiers

colorless dye resulting from destruction of the chromotrope

colored aromatic salt which when in solution is capable of binding to another substance

five-digit code used to indicate the chemical configuration and color of the
dye; dyes of identical structure made by different manufacturers and given different names; will all be given the same color index number.

composition of dyes

chemical group that imparts color to the dye

Gives a dye molecule its ionizing properties ; provides “dyeing” properties and salt-forming properties

Dyes extracted from plants, lichens or insects ; exact chemical composition is unknown; therefore, they cannot be manufactured synthetically

Derived from the heartwood of the logwood tree, Hematoxylin campechianum ; Usually combined with alum or iron salt (acts as a mordant) to form a blue or black colored “lake”

hematoxylin is not a true dye until partially oxidized (ripened)

how is hematoxylin oxidized

how to test potency of Hematoxylin

scarlet dye derived from the ground bodies of female cochineal bug, Coccus cacti

Derived from the stigmas of a plant, Crocus sativus.
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Yellow-red to yellow in its dry orthochromatic state and is yellow in solution.
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It is a “holy dye” used by the Buddhist monks to color their robes

Derived from lichen and requires oxidation to develop its blue-violet color.
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Combined with a weak HCl, it is used for staining elastic fibers (as in van Gieson method)

Derived from the roots of the Madder plant

Derived from a lichen.
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Because of its poor histologic-staining property, it is used extensively as a pH indicator

derived from coal tar and are benzene derivatives

Synthetic dyes usually have greater staining power and permit a broader spectrum of color than natural dyes

Two atoms or groups having two valency bonds replace two hydrogen atoms

substituted groups in quininoid chromophore group must be in what position

This group of dyes has a quininoid ring chromophore
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The structure of these dyes contains 3 cyclic structures which have replaced the 4 hydrogen atoms of
methane (CH₄)

Basic dyes

Acid dyes

Contain a quininoid ring which is the chromophore
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These are derivatives of anthracene

example of Anthra-quininoid group stain

derived from xanthene

examples of xanthene group dyes

an amphoteric dye (carry both (+) and (-) charges.
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Is the product of the oxidation of Hematoxylin

chemical formula of Hematoxylin es

Has a quininoid chromophore where one of the fundamental chromophoric groupings is C=N

inclusions of Quinone-imine group

Have metachromatic properties
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Include: basic dyes (thionine, azures, methylene blue and toluidine)

azines of Quinone-imine group is subdivided to

chromophore of this group of dyes is the group (-N=N-)

Contain 1 azo coupling
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Include: Orange G and Ponceau 2R

Contain 2 azo groups in the dye molecule
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Include: Sudan III,Sudan IV, Oil red O
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These dyes stain fats by a simple physical process (selective solubility)

Contain 3 or more azo groups in their molecule
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Include: Triazo dye and Sirius light blue G

- The chromophore -NO₂ is found in the nitro group of the dyes.
- The chromophore is of such a strongly acid character that the dyes of this group are all acid dyes.
- Picric acid (trinitrophenol)- the most common dye in this group.

These are linear hydrocarbons.
These are very rarely colored

- These are hydrocarbons which include an “aromatic ring” (arene)
- Benzene-the simplest example
- Resonance of the electrons in these rings give the compound the property of color

Dyes are all aromatic compounds

colorless coal-tar derivative
It is the base from which many brilliant synthetic dyes are made offer a wide range in color and action
chemical composition of the dyes may be basic (cationic), acid (anionic) or neutral (amphoteric)In solution, acid dyes are anionic or negatively charged due to ionization of acidic auxochromes such as
carboxyl, hydroxyl and sulphonate groups.

salt of a colored acid (sodium, potassium, calcium or ammonium salt)

colored component (chromophore) is contained in the acid component or the anion

In solution, acid dyes are anionic or negatively charged due to ionization of acidic auxochromes such as carboxyl, hydroxyl and sulphonate groups.

examples of acidic dyes

salt of a colored base (chloride,acetates)

The colored component (chromophore) is found in the base or cationic componentt

colors the nuclei,basophilic granules and bacteria

The acidic component of the tissue attracts the basic dyes

The term “basic” does not refer to the hydrogen ion concentration (pH) of the dye solution

In solution,basic dyes are cationic or positively charged,due to the ionization of the amino auxochrome

examples of basic dyes