[Histonet] PicroSirius red ( PSR) versus Sirius red - Fast Green

[Gudrun Lang]

Hi Carl,
I try a guess. In trichrome-stains the molecular-weight and the
dye-structure are important.
In PSR it is rather a bichrome-stain with picroacid as small dye and
siriusred as big dye, with affinitiy to collagen fibers. Usually the small
dye binds to cytoplasmic proteins, the big one to collagen.
In the Picro-Sirius red-Fast Green stain are three dyes involved, and
Picroacid is the smallest of them, then comes Fast Green and then Sirius
red. The structure of Fast Green is related to Acid Fuchsin, that is also
used as cytoplasma-dye in trichromes (and is smaller than Fast Green).
I think the Picroacid would be the first to stain cytoplasma but competes
with Fast Green and is replaced by the green dye during incubation. - But it
is still important for holding the acidic pH in the staining solution.

I never have done the Sirius Red - Fast Green stain, but in theory it would
be like that. ; )

I hope anyone, who knows better, will correct any mistake.

kind regards
Gudrun Lang


-----Ursprüngliche Nachricht-----
Von: Carl Hobbs via Histonet [mailto:histonet at lists.utsouthwestern.edu] 
Gesendet: Freitag, 24. April 2026 20:57
An: histonet
Betreff: [Histonet] PicroSirius red ( PSR) versus Sirius red - Fast Green

Hi Histonet
Pros and cons re these two methods?
I usually carry out PSR for collagen
( I use the Great  John Kiernan's modification )
Collagen is red, all other tissues are yellow
A new Researcher insists on S.red-Fast Green (SrFg) for quantification
HOWEVER, I note that this also contains Picric acid
How does the Picric acid interact with Fast Green?
Is there a yellow in the SrFg method??
Be grateful for incites before I make this

Be most grateful for advice

Carl


Carl Hobbs FIBMS
Histology and Imaging Manager
Sensory, Pain and Regeneration Centre,
Guys Campus, London Bridge
Kings College London
London
SE1 1UL

020 7848 6810
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