WEEK 3: Common stains in cellular pathology Flashcards
generally, what colour are parts of the cell stained in a H&E stain?
nuclei is black/blue, and everything else is red/pink
what charge does a nuclei acid have?
negative
in H&E, which dye do nuclei acids react with? What colour is produced?
reacts with haematoxylin and turns blue
what gives a positive charge in the body?
cytoplasm, muscle, collagen
does eosin react with positive or negative compartments?
positive
H+E. Which is positive and which is negative dye?
haematoxylin is positive and eosin is negative
what colour does eosin stain?
red/pink
what colour do RBCs give after H+E stain?
orange
what 2 dyes is Van Gieson’s stain composed of?
acid fuchsin and picric acid
what is the principle of Van Gieson’s stain?
Picric acid, small molecules, penetrate all the tissue rapidly, but are only firmly retained in the close textured red blood cells and muscle.
Acid fuchsin, larger molecules, displaces picric acid molecule from collagen fibres, which has larger pores and allow larger molecules to enter.
what does Van Gieson’s stain differentiate?
muscle from collagen (yellow/red)
what is the Masson Trichrome stain used for?
for the detection of collagen fibres in tissues such as skin, heart, etc. on formalin-fixed, paraffin-embedded sections, and may be used for frozen sections as well
what colour is collagen in a Masson Trichrome stain?
blue
what colour is nuclei in a Masson Trichrome stain?
dark blue/ black
what components are stained red in Masson Trichrome stain?
muscle, cytoplasm and keratin
what component does Martius Scarlet Blue stain aim to show?
fibrin
what are the results for fibrin in Martius Scarlet Blue stain?
early deposits are yellow, mature fibrin is red
what is the purpose of silver impregnation?
Impregnation of tissue to enhance the contrast in tissues (not a staining with dye!)
what are disadvantages to silver impregnation?
expensive and can be unreliable
how is silver located in silver impregnation?
black show fine deposits of silver atoms
how does silver impregnation work?
Silver ions (Ag+) reduced to silver atoms (Ag) in reduction reactions at sensitive sites (e.g. aldehyde groups)
what are the 3 ways of producing metallic silver in silver impregnation?
1.Argentaffin reaction –argentaffin or enterochromaffin cells of the gut only due to strong reducing pigment.
2.Argyrophil reaction –external reducer needed e.g. formalin (Reticulin fibres, neuroendocrine cells, neurons & axons).
3.Ion-exchange reactions (e.g. phosphates/carbonates of mineralized bone in von Kossa stain).
what is reticular tissue?
a special type of connective tissue that predominates in various locations that have a high cellular content.
how is reticular tissue arranged?
It has a branched and mesh-like pattern, often called reticulum, due to the arrangement of reticular fibres (reticulin). These fibres are actually type III collagen fibrils.
where is reticular tissue located in the body?
Found in e.g. the kidney, liver, the spleen, lymph nodes, Peyer’ patches and bone marrow. Functions as a ‘soft skeleton’
what method is usually used to identify reticulin fibres?
silver impregnation method
what can the structure of reticulin fibres show?
they reflect function and can show liver fibrosis or cirrhosis and bone marrow fibrosis
what colour do reticulin fibres appear in silver impregnation method?
dark brown or dark grey
which cells produce reticulin?
reticular cells
why do some protocols use neutral red at the end of the reticulin protocol?
it is used as a nuclear counterstain as a last step before dehydration.
what is the Von Kossa stain used for?
Von Kossa stain is widely used in histology to detect the presence of abnormal calcium deposits in the body
what is the principle of the Von Kossa stain?
Silver impregnation technique. The principle of this coloration is based on the transformation of calcium salts into silver salts: calcium ions, bound to phosphates, are replaced by silver ions brought by a solution of silver nitrate
what is amyloid?
an abnormal protein, amino sequences similar or identical to body proteins
why are amyloids “bad”?
they form insoluble fibrils that are resistant degradation
how are amyloids detected?
with Congo red, polarised light shows green birefringence
how are carbohydrates identified?
with PAS stain. Turns pink
what is the function of mucus?
Mucus provides physical protection and hydration, excludes pathogens, and is a reservoir for antimicrobial molecules.
what is the main component of mucus?
mucin glycoproteins
how are goblet cells stained?
AB/PAS. Not H+E
what are 2 important lenses in fluorescent microscope
condenser lens, objective lens.
how are fluorescent molecules used in a fluorescent microscope?
they’re used to label cellular structure of interest to stand out from the cell.
