Structure and Arrangement of Salivary Gland Chromosomes in Drosophila Species

Abstract

The salivary gland nuclei in Drosophila contain two different chromosome derivatives, the long chromosome strands which correspond to the euchromatic parts of prophase chromosomes, and the chromocenter which arises from the heterochromatic regions (Heitz [2]). While most investigators now agree that the euchromatic strands are composed of a number of closely united chromonemata, the homologous chromomeres of which form discs (aggregate chromomeres), there is no uniformity of opinion regarding the chromocenter. Painter [3] considered it an aggregate of accessory material into which each chromosome sends a thin achromatic strand. Muller and Prokofjeva [4] believe that these regions show the same regular banding as the euchromatic parts. Koller' calls the chromocenter an "undifferentiated magma."