High Voltage (1MeV) EM image of metaphase chromosomes isolated from CHO cells using a non-aqueous techniqe, squashed in 1:1 acetic acid:ethanol and transferred to an EM grid. A chromatid pair occupies the center of the image. This micrograph was captured at a specimen tilt of 45 degrees. The accompanying image has a tilt of 55 degrees, creating a stereo pair that provides an oblique stereo view of the chromatids.
Cells were metaphase arrested with thymidine followed by colcemid, then exposed to a low ionic strength swelling medium (0.07M phosphate buffer). Chromosomes were isolated by the non-aqueous hexylene glycol technique of Wray and Stubblefield, squashed in 1:1 acetic acid:ethanol,stained, and transferred to an EM grid. See also: H. Ris 1981 Stereoscopic electron microscopy of chromosomes. Meth Cell Biol 22:77-96 H. Ris 1978 Preparation of chromatin and chromosomes for electron microscopy. Meth Cell Biol 18:220-246.
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