Connective Tissue, Muscle, and Nerve Stains Flashcards
What is used to postfix before performing a Trichrome stain?
Bouin because of the picric acid.
Nervous system tissue stains fall into 3 categories. What are they?
Neuronal cell bodies and processes, glial cells and processes, and the myelin sheath.
Why is Weigert Iron Hematoxylin used in the Trichrome Stain instead of an aluminum mordanted hematoxylin?
Iron hematoxylin won’t be decolorized by the subsequent acid dye steps.
Give reasons why any hematoxylin cannot be substituted for the iron hematoxylins in muscle, nerve and elastic stains?
Aluminum hematoxylin would be decolorized by the acid dyes in the Trichrome and Mucicarmine stains. Neither myelin nor elastin is demonstrated with aluminum hematoxylin.
Why is the Trichrome stain called the Trichrome stain?
There are 3 dyes in the staining procedure. In a Masson’s Trichrome, these are Wiegert Hematoxylin, Biebrich Scarlet-Acid Fuschin, and Aniline Blue.
What does Verhoeff Hematoxylin stain in addition to nuclei?
Elastin
What is the Bielschowsky’s stain?
A double impregnation silver stain used to demonstrate nerve fibers, neurofibrillary tangles, and amyloid plaques.
What one stain demonstrates collagen, elastic fibers, muscle, mucin, and fibrin?
Movat’s Pentachrome.
What stain shows mucin, ground substance, and C. neoformans blue?
Movat’s Pentachrome.
Name 2 basement membrane stains.
PAS, PAMS, Jones. Jones is shown.
How can you demonstrate fat in paraffin embedded tissue?
By fixing in osmium tetroxide.
What is the usual counterstain for a Sudan Black?
Nuclear Fast Red.
What is the usual counterstain for an Oil Red O?
Hematoxylin.
Why must you use aqueous mounting media for fat stains?
For the same reason we can’t use alcoholic fixatives, or routine processing, or paraffin embedding to demonstrate fat: The solvents would dissolve the fat. Shown are FFPE fat cells.
The Oil Red O demonstrates lipid. Why might a pathologist order it?
Fat embolus, myelin degeneration, liposarcomas. A fat embolism is pictured.
The lipid dyes are more soluble in fat than in the staining solution (often propylene glycol and isopropanol) it is dissolved in. What do you call this dye binding technique?
Absorption. When a dye is more soluble in the tissue component to be stained than in the solution it is made in, that is called Absoption.
What does the LFB or Luxol Fast Blue demonstrate?
Myelin. Like Alcian Blue, the blue color comes from copper.
What does the Cresyl Echt Violet stain demonstrate?
Nissl substance, basophilic RNA involved in protein synthesis.
The LFB stain is paired with many other stains such as Holmes and PAS. Which one is pictured?
CEV. The LFB-CEV stain is pictured.
What does the Trichrome stain demonstrate?
Fibrosis, by differentiating between collagen and muscle.
True or False: Osmium tetroxide stains as well as fixes tissue.
True. Fixing EM specimens with Osmium tetroxide gives great preservation of the plasmalemma and cytoplasm, but both EM and LM (light microscopy) specimens can be stained with osmium tetroxide. The picture demonstrates myelin on the axons of nerve fibers. Osmium tetrooxide both preserves and stains lipids well.
