Correlation of pachytene chromomeres and metaphase bands of human chromosomes, and distinctive properties of telomeric regions.

By means of double staining with DAPI and chromomycin A3, we show that the chromomeres of human pachytene chromosomes are generally DAPI positive and chromomycin negative, like the G- or Q-bands of mitotic chromosomes. Thus we have demonstrated, using an objective technique not based on morphological comparisons, that chromomeres and G-bands are equivalent. However, terminal chromomeres and the ends of mitotic chromosomes, as well as a few other sites, are chromomycin positive and DAPI negative. The ends of human chromosomes appear, therefore, to contain a distinctive class of GC-rich DNA.