The arrangement of interphase chromosomes: Structural and functional aspects

The arrangement of chromosomes in the interphase nucleus has intrigued scientists for over a century. Chromosomes are best visualized as condensed mitotic structures which allow the consistent recognition of landmarks such as the centromere and nucleolus organizer. However, these condensed structures are usually genetically inactive, for it is in interphase, when chromosomes are not discernible, that most gene activity occurs. In this review we examine the functional significance of interphase chromosome associations as well as the results of the application of techniques now available for determining the positions of interphase chromosomes. The arrangement of special structures such as the nucleolus, constitutive and facultative heterochromatin, centromeres, and telomeres will be emphasized.