Nucleoli visualized by silver staining combined with a new RNA-specific fluorochrome.

A technique for distinguishing nucleolar components by light microscopy is described. Silver staining is used for localizing nuceolar-organizing regions. A new RNA-specific fluorochrome, 4''-6-bis(2'-imidazolinyl-4'-5'H)-2-phenyl-4'-phenoxyindole, visualizes the RNA-containing "partes fibrillares et granulares" of the nucleolus. Both staining procedures can be combined to analyze nucleolar structure and function by light microscopy.