I'd suggest as a control normal liver or brain, selected for abundant - what 
was once called "wear and tear pigment". The control should be fixed and 
processed the same way the material being examined is.

The word is "lipofuscin" - pronounced ligh-po-FUSS-in, derived from a Latin 
word "fuscus" which can mean brown, yellow, or dark. The dye name "fuchsin" - 
FYOOK-sin - is derived from a flower called a fuscia (FYOO-sha) which was 
named after someone with the German name Fuchs (pronounced FOOX). 

The seaweed Fucus (whence fucose) is etymologically unrelated, as is, well, 
like, y'know, forget it....

Bob Richmond
Samurai Pathologist
Knoxville TN