STAINS AND STAINING SOLUTIONS Flashcards
• Stains are prepared from two categories of dyes:
Natural dyes
Synthetic dyes
Natural Dyes
Hematoxylin
Cochineal Dyes
Orcein
Saffron
Synthetic Dyes
Aniline
Coal Tar dyes
are those obtained from plants and animals, previously utilized for dyeing of wool and cotton.
Natural dyes
Hematoxylin is a natural dye derived by extraction from the core or the heartwood of a Mexican tree known as
“Hematoxylin Campechianum”.
It is by far the most valuable staining reagent used by the cytologist due to its powerful nuclear and chromatin staining capacity, and its striking polychrome properties which may be produced with proper differentiation.
It may be used after almost any fixative and is a permanent stain.
Hematoxylin
Hematoxylin itself is not a true basic dye.
The active coloring agent is____, which is formed by the oxidation of hematoxylin, a process known as “____.”
hematin
ripening
This is usually accomplished by exposing the substance to_____ or _____, thereby oxidizing hematoxylin (natural ripening).
air and sunlight
Ripening
Such a process is slow and takes as long as______, but it can be accelerated by adding strong oxidizing agents such as (5) which converts hematoxylin to hematin almost instantaneously by chemical oxidation (artificial ripening), so that the staining solution is ready for use immediately after preparation.
3-4 months
hydrogen peroxide
mercuric oxide
potassium permanganate
sodium perborate
sodium iodate
Ripening
It is essential that the____ be used in correct amount, since excessive oxidation (over-ripening) leads to production of other useless compounds.
Using the least amount of ____ will result in satisfactory staining and longer life of the stain.
oxidant
Ripened hematoxylin is seldom used alone due to its inherent low affinity for the tissue itself.
It is most frequently used in combination with (4), which act as mordants catalyzing or forming links between the hematin stain and the tissue.
alum
iron
chromium
copper salts
….stains are recommended for progressive staining of tissues, and are usually counterstained with Eosin, Congo Red and Safranin.
Alum hematoxylin stains
Both the Ehrlich’s solution and the Harris’ solution contain…
Alum Hematoxylin
Rapid ripening of:
Ehrlich’s reagent, however, is brought about by the addition of______;
Harris solution is ripened with_____.
Sodium Iodate
Mercuric Chloride
are used only for differential or regressive staining, using Acid-Alcohol as a differentiating agent.
Iron hematoxylin compounds
An example of an Iron Hematoxylin compound is_____ Stain using Iron (Ferric) Chloride
Weigert’s
…solutions are utilized for the study of spermatogenesis.
Copper hematoxylin
In a skillfully made H & E preparation the red blood cells are almost____, and collagen and cytoplasm (especially muscle) acquire different shades of___
orange
pink
is an old histologic dye extracted from the female cochineal bug (_____), which is treated with____ to produce the dye,_____.
Cochineal dye
Coccus Cacti
alum
carmine
It is widely used as a powerful chromatin and nuclear stain for fresh material and smear preparations.
Cochineal dye
Cochineal dye
When combined with picric acid (______), it is extensively used in neuropathological studies;
and when combined with aluminum chloride (______), it is used for the demonstration of glycogen.
Picrocarmine
Best’s carmine stain
is a vegetable dye extracted from certain lichens which are normally colorless, but which, when treated with ammonia and exposed to air, produce blue or violet colors.
Orcein
Color of orcein
Blue to violet
It is a weak acid, is soluble in alkali, and is mainly used for staining elastic fibers.
Orcein
is also obtained from lichens, treated with lime and soda, and exposed to ammonia and air. It is, however, not used as a cytological stain because of its poor staining property. It is instead, used mainly as an indicator.
Litmus
Synthetic dyes are sometimes known as “______” since they were originally manufactured from substances that have been taken from coal tar.
Coal Tar Dyes
Coal Tar Dyes/ Synthetic dyes
They are derived from the hydro-carbon benzene (C6 H6 ), and are collectively known as
Aniline Dyes
are substances with definite atomic groupings and are capable of producing visible colors
Chromophores
Simple benzene compounds which contain such substances (chromophore) are known as
chromogens