Figure 6.

Chromosome territory structure and transcription sites. The cartoon shows a thin section of an interphase nucleus, highlighting a single chromosome territory only. The chromosome fiber is shown, which follows an irregular and convoluted path in the chromosome territory, similar to the chromonema fiber proposed by Belmont and Bruce 1994. In the section, the chromosome fiber is cut perpendicular, oblique, and parallel with respect to the fiber axis. Often, different parts of the chromosome fiber come close together, forming compact subchromosomal domains (gray areas), in which the individual fiber cannot be distinguished. Transcriptionally active chromatin is markedly compartmentalized. Active loci (indicated by black rectangles) are located predominantly at or near the surface of compact chromatin domains. The interchromatin space inside a chromosome territory is continuous with the interchromosomal domain.