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High Voltage (1MeV) TEM image of a squash preparation of polytene chromosomes from salivary gland of 3rd instar larva of Drosophila melanogaster showing the band-interband organization.

Technical Details

Salivary glands were dissected, exposed to 0.07 M KCl, fixed in 3:1 acetic acid:ethanol and squashed in 50% acetic acid. Slides were frozen in liquid nitrogen, the cover slip removed, and the slide immersed in 1% uranyl acetate for 5 min followed by dehydration in ethanol and transfer to amyl acetate. 2% parlodion in amyl acetate was spread over the slide and allowed to air dry. Areas for observation were scored, released by water immersion, picked up on formvar-coated grids 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.

Biological Sources

NCBI Organism Classification
Drosophila melanocephala
Cell Type
salivary gland
Cellular Component
polytene chromosome


Hans Ris


This image is part of a group.


Image Type
Imaging Mode
Parameters Imaged
electron density
Source of Contrast
differences in adsorption or binding of stain
Visualization Methods
uranyl salt
Processing History
unprocessed raw data

Sample Preparation

chemically fixed tissue
coagulating-fixative fixed tissue
Relation To Intact Cell
whole mounted tissue
chromosome squash


Spatial Axis Image Size Pixel Size
X 6566px 2.5nm
Y 4209px 2.5nm
*CIL – Cell Image Library accession number. Please use this to reference an image.