MLT GlobeHistopathology: H&E and routine staining
45 Histopathology MCQs on H&E and routine staining with answers and explanations.
In haematoxylin staining, alum acts as a link that binds the dye to tissue. Such a link substance is called a:
A mordant (e.g. aluminium or iron salts) forms a dye–metal lake that attaches to tissue; accentuators only speed or intensify staining without forming a lake.
In regressive H&E staining, excess haematoxylin is removed from overstained sections with:
Differentiation uses a weak acid to extract surplus dye; the alkaline solutions listed are used for bluing.
Which synthetic resin is the mounting medium most widely used for routine H&E slides?
DPX is a quick-drying, xylene-miscible resin; glycerine jelly and Farrant's are aqueous mountants, and Canada balsam is a natural, slow-drying resin.
Which statement about eosin is correct?
Eosin is a synthetic xanthene acid dye; haematoxylin is the natural logwood dye that stains nuclei.
Which solution is commonly used to blue haematoxylin after differentiation?
Mild alkalis (Scott's solution, ammonia water, lithium carbonate) turn the red haematoxylin lake blue; acid alcohol does the reverse.
Paraffin sections are prepared for aqueous staining. Which step comes LAST before the stain?
Sequence: warm to melt wax, xylene to dewax, alcohols to remove xylene, then water so aqueous stains can penetrate.
In an H&E section, which structures appear blue-purple?
Haematoxylin stains nucleic acids blue-purple; eosin colours cytoplasm, collagen and red cells in shades of pink.
The brief rinse in weak acid that removes excess haematoxylin is called:
Differentiation selectively extracts surplus dye; bluing follows it in alkaline water.
In histotechnology, 'mounting' means:
Mounting protects the stained section and gives optical clarity; dewaxing and pick-up are earlier steps.
Which feature is UNDESIRABLE in a mounting medium?
A mountant should be colourless so it does not alter stain colours; it should dry quickly, match glass and preserve stains.
Harris, Mayer's, Ehrlich's and Delafield's are all varieties of which stain?
These are named alum haematoxylin formulations used as nuclear stains.
In routine H&E sections, which dye supplies the pink counterstain to cytoplasm, collagen and muscle?
Eosin Y is the standard general-purpose cytoplasmic counterstain. Congo red is used for amyloid; acid fuchsin and Biebrich scarlet appear mainly in special trichrome-type methods.
Which sequence correctly brings a paraffin section down to water before staining?
Wax is first dissolved in xylene, xylene is removed by absolute alcohol, then descending alcohols rehydrate the tissue before water. The reverse order is used after staining for dehydration and clearing.
After an H&E stain is complete, what must be done before the section is mounted in a resinous medium such as DPX?
Resinous mountants are immiscible with water, so the section is dehydrated in ascending alcohols and cleared in xylene. Mounting wet sections in DPX causes cloudiness and poor preservation.
Removing paraffin wax from a section on a slide with xylene before staining is commonly called:
Deparaffinization is also called dewaxing. Infiltration and impregnation describe wax entering the tissue during processing; dehydration is removal of water by alcohol.
A bottle of resinous mountant has thickened and is difficult to spread. What is the appropriate way to thin it?
Resinous mountants are dissolved in xylene or toluene, so adding a little of that solvent restores working viscosity. Aqueous or acid reagents are immiscible and would cloud the medium.
After placing a coverslip, trapped air bubbles are best expelled by pressing gently from the centre outward with:
Gentle, even pressure with the back of forceps spreads the mountant and pushes bubbles out without smudging or cracking the coverslip. Fingers leave prints and blades may scratch or break the glass.
Which form of eosin is standard for the counterstain in routine H&E?
Eosin Y, the yellowish tetrabromofluorescein salt, is the routine counterstain. Eosin B and phloxine are occasionally added or substituted but are not the standard reagent.
Dried excess mountant around a coverslip is best removed with:
Hardened resin is scraped off with a blade and the residue wiped with its solvent, xylene. Water and acid alcohol do not dissolve resinous media.
Canada balsam and gum dammar are best classified as:
Both are plant-derived resins dissolved in xylene for mounting sections. They have largely been replaced by synthetic resins because they yellow and become acidic with age.