High Voltage (1MeV) TEM image of a 'thick' section of polytene chromosome from salivary gland of 3rd instar larva of Drosophila melanogaster showing the band-interband organization. This image was captured with a specimen tilt of 56 degrees. Grouped with it is an image of the same region taken at a tilt angle of 45 degrees, providing an oblique stereo view of the structure.
Salivary glands were dissected, fixed with paraformaldehyde, post-fixed with osmium tetroxide, and embedded in plastic. 4 micron sections were cut, stained with aqueous uranyl magnesium acetate, and observed with the Wisconsin HVEM at 1 MeV. See Ris, H 1981 Stereoscopic Electron Microscopy of chromosomes. Meth Cell Biol 22:77-96; Ris, H 1978 Preparation of chromatin and chromosomes for electron microscopy. Meth Cell Biol 18:229-246