Aldehyde Toluidine Blue
for Mast Cells

Solutions

Nuclear fast red

Tartrazine, 0.1% aqueous

Solution A
Toluidine blue	2.5	g
Ethanol, 70%	500	mL
Paraldehyde, fresh	5	mL
Hydrochloric acid, conc	5	mL

Dissolve the dye in the ethanol. Add paraldehyde and acid.

Ripen one week at room temperature. Store at room temperature.

Filter before use. Stable for a year or longer.

Tissue sample
5µ paraffin sections of neutral buffered formalin fixed tissue are suitable.
Other fixatives are likely to be satisfactory.

Method

1. Bring sections to water via xylene and ethanol.
2. Rinse with 70% ethanol.
3. Place in solution A for 1 hour.
4. Wash off excess stain with 70% ethanol.
5. Rinse well with tap water.
6. Counterstain with nuclear fast red-tartrazine.
7. Dehydrate with ethanol, clear with xylene and mount with a resinous medium.

Expected results

• Mast cell granules  –  deep blue
• Nuclei  –  red
• Background  –  yellow

Notes

1. The staining solution is a modification of Gomori's aldehyde fuchsin using toluidine blue instead of basic fuchsin.
2. Staining time may need to be increased as the solution ages (up to 2 hours).
3. Elastic fibres are unstained, likely because basic fuchsin can form dipole-dipole interactions and toluidine blue generally does not.
4. Mucins are stained very pale blue.
5. Different samples of this dye may vary in effectiveness. If a sample gives pale staining, try one from another vendor. Toluidine blue from Fisher Scientific was used to develop the method.

 

Reference

Llewellyn, B. D., unpublished.