Palmgren's Silver Impregnation
for Peripheral Nerves
Materials
Solution A
| Material | Amount | |
|---|---|---|
| Concentrated formalin | 25 | mL |
| Nitric acid, 1% aqu. | 0.2 | mL |
| Distilled water | 75 | mL |
Solution B
| Material | Amount | |
|---|---|---|
| Silver nitrate | 15 | g |
| Potassium nitrate | 10 | g |
| Glycine, 5% aqu. | 1 | mL |
| Distilled water | 100 | mL |
Solution C
| Material | Amount | |
|---|---|---|
| Pyrogallol | 5 | g |
| Nitric acid, 1% aqu. | 1 | mL |
| Absolute ethanol | 275 | mL |
| Distilled water | 225 | mL |
Solution D
| Material | Amount | |
|---|---|---|
| Gold chloride | 1 | g |
| Acetic acid, glacial | 0.2 | mL |
| Distilled water | 200 | mL |
Solution E
| Material | Amount | |
|---|---|---|
| Aniline | 4 | drops |
| Ethanol, absolute | 100 | mL |
| Distilled water | 100 | mL |
Solution F
| Material | Amount | |
|---|---|---|
| Sodium thiosulfate | 5 | g |
| Distilled water | 100 | mL |
Tissue Sample
5µ paraffin sections of neutral buffered formalin fixed tissue are suitable. Chrome, mercury and osmium fixatives should be avoided.
Protocol
- Bring sections to water via xylene and ethanol.
- Celloidinise sections.
- Place into solution A for 15 minutes at room temperature or for 5 minutes at 35°C.
- Rinse with distilled water, three times over 5 minutes.
- Do not rinse with water. Place into fresh solution C at 45°C for one minute. Agitate continuously.
- Rinse with 50% ethanol.
- Rinse thoroughly with distilled water, three times over 5 minutes.
- Optionally, tone with solution D to the colour wanted.
- Place into solution E for 15 seconds, agitating continuously.
- Rinse with tap water.
- Fix with solution F for 5 seconds.
- Rinse well with tap water.
- Dehydrate with ethanol, remove celloidin and clear with xylene. Mount with a resinous medium.
Expected Results
- Nerve fibers – dark brown (untoned) or black (toned)
- Background – lighter brown (untoned) or grey (toned)
Notes
- Toning with gold chloride (solution E) may be applied at step 8. Many workers find the black on grey scheme less satisfactory than dark brown on light brown.
- If the nerve fibers are poorly shown, the impregnation may be intensified by repeating steps 2-7, but at lower temperature and shorter times. Toning and intensifying (steps 7-9) may also be repeated. These repetitions are often unsatisfactory.
- If not celloidinised, the preparations may have a coarse precipitate of silver.
- Although originally designed for the peripheral nervous system, Palmgrens silver impregnation may also be found useful for the central nervous system.
Safety Note
Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.
References
- Drury, R.A.B. and Wallington, E.A., (1980)
Carleton’s histological technique Ed. 5
Oxford University Press, Oxford, UK.
