The effect of graded 60°C 1N nitric acid extraction and of deoxyribonuclease digestion on nuclear staining by metachrome mordant dye metal salt mixtures

We can divide metachrome mordant staining of nuclei after graded 60°C 1N nitric acid extraction into three groups. The feulgen nucleal reaction and dilute cationic dye staining of nuclei are abolished in about 30 minutes. With one group of metachrome dyes nuclear staining is lost with acid exposures of one hour or less. In a second group nuclear staining is weakened by 30–60 minute extractions, but persists in recognizable grade for 4–6 hours. In the third group nuclear staining remains almost unimpaired for 4–6 hours.