Abstract: | The principles of three dimensional organization of primary and secondary orders polytene chromosomes in ovarian nurse cells of Drosophila melanogaster were elucidated. Contrary to somatic tissues, no joining of chromosome arms into local chromocentre was discovered. The chromosomes are separated in the nuclear space and are attached to the nuclear envelope by the centromeric (and the XL arm--by the telomeric) sites, the arms of autosomes (especially primary polytene chromosomes) being separated in the area of attachment. Polytenized XR arm of the X chromosomes were discovered. The architecture of chromosomes discovered in ovarian nurse cells is tissue-specific and differs considerably from the organization of polytene chromosomes of somatic tissues. |