188.8.131.52.2. Toluidine staining
Toluidine staining (Fig. 3) is applied to semi thin sections of epoxy embedded tissue (section 184.108.40.206). The stained sections can be used to determine the area of interest for further processing, but also for LM observations. Toluidine stock solution is obtained from commercial sources.
The 1 % toluidine blue and 2 % borate in distilled water needed is obtained by mixing:
- 1 g toluidine blue O
- 2 g sodium borate (borax)
- 100 ml distilled water
- Dissolve the sodium borate in the water
- Add the toluidine blue powder
- Stir until dissolved
- Filter the stain solution (use syringe filter) before use
Note: The borax makes the stain alkaline so it will help penetrating to
the epoxy sections
- Cut semi-thin sections at 0.5 - 1.0 μm
- Transfer sections to a drop of distilled water on a glass slide.
- Dry sections on a glass slide on a slide warmer or over a 40 W lamp
- Cover section with staining solution (with the heat source still on) for 1-2 minutes
- Rinse off excess stain with distilled water and air
Fig. 3. Toluidine staining of a semi thin section of epoxy embedded ventricular tissue. Photo: I Fries.