Stock 1% Toluidine Blue in 1% Borate.

Toluidine Blue 1 gm

Sodium borate 1 gm

Deionized water 100 ml

Dissolve the sodium borate in the water, then add the stain powder and stir until dissolved. Filter the stock solution.

Staining.

Dry sections down on a glass slide. Cover with a puddle of stain and heat on a warm hot plate for 30 to 120 seconds, or until the puddle steams. Rinse off excess stain gently with distilled water or 70% ethanol. Dry the slide on the hot plate then coverslip the cooled slide with DPX.

The stock 1% toluidine blue is a powerful and effective stain for epoxy sections. Dilute 10-fold to 0.1% with 1% sodium borate to lightly stain sections to be used for autoradiography.

Notes: DPX will cause sections of Spurr's epoxy to wrinkle unless mounted on carefully cleaned slides.

Be careful not to overheat the wet sections or steam bubbles may form under them.

Methacrylate sections may need shorter stain times to prevent high background from stain bound to the plastic. A brief rinse with 70% ethanol will remove this background at the risk of loosening the section from the slide.

Mercer, E.H., J. Royal Microscopy Society 81:179 (1963).

Burns, W.A., "Thick Sections: Technique and Applications", Diagnostic Electron Microscopy, Ch. 4, B.F. Trump and R.J. Jones, eds., John Wiley & Sons, New York, 1978.