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A copper block method for freezing non‐cryoprotected tissue to produce ice‐crystal‐free regions for electron microscopy
Author(s) -
Dempsey G. P.,
Bullivant S.
Publication year - 1976
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1976.tb02406.x
Subject(s) - electron microscope , liquid nitrogen , ice crystals , copper , cryofixation , materials science , fibril , macromolecule , block (permutation group theory) , biophysics , crystallography , chemistry , optics , biology , physics , biochemistry , geometry , organic chemistry , mathematics , metallurgy
SUMMARY Two methods are described for fracturing unfixed, uncryoprotected mouse liver that had been frozen by contact with a copper block at liquid nitrogen temperature. The best method involved precise fracturing of a few microns of surface tissue with a cooled glass knife, using the Cryokit attachment of the LKB III ultramicrotome. The resulting replicas were free from electron microscopically‐visible ice crystals. A noticeable feature of replicas from unfixed, uncryoprotected tissue was the extent of plastic deformation of certain cellular structures. Cytoplasmic macromolecules, and to a lesser extent intramembranous particles, often appeared to be ‘stretched’ to form fibrils.