Masson Trichrome

Classification: connective tissue stain 

Mechanism of staining: porosity

Purpose: stain collagen 

Control tissue: skin, intestine

Properly Stained Slide

Grey/black: Nuclei

Bright red: Muscles, RBC

Dull red: Cytoplasm






Iron Hx (Weigert’s)

Nuclear stain

Ionic bonding

Omitted: No nuclear staining.

Too short: Since it is a progressive stain, do not perform the differentiating step.

Too long: Not an issue- can be corrected at a later step with a differentiator.

Ponceau 2R

Stains acidophilic tissues


Omitted: Nuclei and cytoplasm will not be demonstrated.

Too short: Nuclei and cytoplasm will not be demonstrated or weakly stained.

Too long: Will obscure the target tissue.

Phospho-myolybdic acid

Used as a differentiator. Acts to remove acid fuchsin from collagen fibers.

Works to trap acid fuchsin in RBC, muscle & cytoplasm.


Omitted: Light green counterstain will enter the target muscle.

Too long: Acid fucshin will be removed from the muscle components.

Too short: Light green secondary counterstain will entre the muscles.

Light green

Stains collagen fibers. Works as a counterstain.

Salt linkage and porosity

Omitted: Collagen will not be demonstrated.

Too long: Counterstaiin will appear dark and may interfere with the staining of muscles.

Too short: Collagen will be stained pale.

Acid alcohol

Removes excess counterstain


Omitted: Without acid alcohol there will be an excess of background staining which will obscure the nuclear detail.

Too long: No nuclear detail will be present since the tissue is now overdifferentiated.

Too short: Since this step only includes one dip the alternative is no dips and that would result in no nuclear detail.



Officer B. HIML251 Lecture notes: Alcian Blue and Masson Trichrome stains, January 28, 2009