Masson/Fontana for melanin
Masson, 1914; Fontana, 1912.
Use a positive control section.
Melanin (also argentaffin, chromaffin and some lipofuscins) - black.
Nuclei - red.
To 20mls of 10% silver nitrate add conc. ammonia drop by drop until the formed precipitate almost dissolves leaving a slight opalescence. This may take many drops. If the precipitate completely redissolves add a drop or two of 10% silver nitrate until opalescence is achieved. Always mix and leave for a few seconds between drops. Finally dilute with 20mls of distilled water. Make up fresh each time.