Chromosome polytene
The chromosomes polytenes (or polytenic ) are present in the cells of certain bodies of the Larve S of Diptère S (the salivary Glandes for example). They correspond to a certain number of copies of the Chromatides (up to 1000) which remained welded between them. The Coloration of Feulgen makes visible, with the photonic Microscope, of the strongly coloured bands, corresponding to the position of the Gènes, and the clearer bands (interbanded), the intergenic areas.
One calls puffs the slackened diffuse areas of the chromosome polytenic. They are sites of the transcription in ARN. A ring of Balbiani is a puff of large size on the chromosome. It draws its name from its discoverer Edouard Balbiani (1823-1899).
The chromosomes polytenes were largely studied by Calvin Blackman Bridges, collaborator of Thomas Hunt Morgan.
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