Polytene chromosomes from the salivary gland cells of Drosophila melanogaster larvae have been the most useful model for studying the functional morphology of interphase eukaryotic chromosomes since their discovery almost 70 yr ago (1). The question remains as to whether the polytene structure is universal. How similar is the organization of polytene chromosomes in different tissues, because cell differentiation may lead to diverse functional chromosome states? The greatest difference can be expected to be seen between the chromosomes of the germ-line cells and the cells of somatic tissue.
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