Color Differences in Heated and Giemsa Stained Mouse Chromosomes

Denaturation by heating in distilled water at 85-100 C for 30 seconds results in color changes of Giemsa stained chromatin. Standard cytogenetical preparations from lymphoid tissues of normal and leukemic mice show violet-purple chromasoma After denaturation in the presence of formaldehyde deep blue chromosomes are observed. Rapid cooling of heat-denatured slides results in chromosomes with violet-purple centromeric heterochromatin and pale blue or pale violet-blue arms. The color difference disappears when heating is followed by incubation at 65 C. In this case only differences in staining intensity are found between centromeric heteruchromatin and arms.