Nucleolar Definition in Hemalum and Eosin Staining

This investigation was designed to clarify why routine hemalum and eosin staining so frequently demonstrates nucleoli in a distinctive purple to red shade. Participation of eosin in the effect suggests that nucleolar basic protein is being stained, and this fact has been confirmed with bromphenol blue. Dye affinities of the nucleolus have been further studied by successively substituting basic and acid fuchsin for the pyronin in the standard Unna-Pappenheim mixture. At pH 4.8 it appears that the nucleolus has both acid and basic groups freely available for staining.