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Special Stain - Von Kossa

  • Calcium staining
  • Von Kossa Technique

Silver is substituted for calcium in calcium salts. This silver salt is then reduced to black metallic silver by the use of light or photographic developer.


Information on how to perform the technique is listed below.

1.     Take sections to distilled water

2.     Place in a premade 1.5% Silver nitrate in the dark for 10-20 minutes. Check solution to make sure it has not gone off as well.

3.     Rinse in distilled water

4.     Reduce in freshly prepared 0.5% hydroquinone - 5 minutes.

3.     Rinse in distilled water

4.     Treat with 5% sodium thiosulphate (Hypo) – 3 minutes

3.     Rinse in distilled water

4.     Counterstain in Nuclear Fast Red - 5 minutes.

5.     Dehydrate, clear and mount .


Calcium deposits - Black

Background - Red

Below is a picture of a Von kossa stain, as you can see the calcium in black stands out clearly in the background, made easier to see thanks to the counterstain of nuclear fast red making this a useful test for calcium deposits

Photo - Von Kossa Stain