Heterochromatin and Euchromatin

Within the chromatin of a eukaryotic nucleus, not all regions are equally condensed. Heterochromatin -- a term proposed by Heitz -- refers to segments of the chromosome that stay tightly condensed through interphase and early prophase; these regions cluster near centromeres and telomeres (and are also scattered elsewhere), stain darkly, are two to three times richer in DNA than euchromatin, and …