Prepared by
ROY ELLIS
IMVS Division of Pathology
The Queen Elizabeth Hospital
Woodville Road, Woodville, South Australia 5011
PRINCIPLE
Melanin is always intracellular, and varies from pale to dark brown in natural colour. It is normally found in hair, retina, skin, and substantia nigra of the brain.
TECHNICAL POINTS
1. A known melanin containing positive control section must be used.
2. (step 5) - Check microscopically that the bleach step has been successful on the control.
3. Steps 6 to 13 may be performed on the staining machine.
METHOD
1. Bring sections to distilled water.
2. Oxidise with potassium permanganate 5 min
3. Wash in running tap water
4. Decolourise in oxalic acid 1 min
5. Wash in running tap water
6. Counterstain nuclei with haematoxylin 1 min
7. Wash in running tap water
8. Differentiate with acid alcohol
9. Wash in running tap water
10. Blue in Scotts tap water
11. Rinse in running tap water
12. Counterstain with eosin 1 min
13. Dehydrate, clear and mount.
RESULTS
melanin.....................................colourless
nuclei........................................blue
erythrocytes................................pink
cytoplasm...................................pale pink
REAGENT FORMULAE
1. 1% aq potassium permanganate
2. 2% aq oxalic acid
REFERENCE
Lillie, R. 1965. ‘Histopathologic Technique and Practical Histochemistry’, 3rd edition, McGraw-Hill