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Freeze Substitution for EM-Studies Time Measuring.

Published online by Cambridge University Press:  02 July 2020

Migunova R.K.
Affiliation:
Institute for Problems of Cryobiology and Cryomedicine of the National Academy of Sciences of Ukraine., Kharkov, Ukraine. E-mail: [email protected]
Todrin A.F
Affiliation:
Institute for Problems of Cryobiology and Cryomedicine of the National Academy of Sciences of Ukraine., Kharkov, Ukraine. E-mail: [email protected]
Kaprelyants A.S.
Affiliation:
Institute for Problems of Cryobiology and Cryomedicine of the National Academy of Sciences of Ukraine., Kharkov, Ukraine. E-mail: [email protected]
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Extract

We conducted physical and mathematical modelling of the process of substituion of ice with organic solvent. The result was a relationship between the time of freeze-substitution and the sample thickness. The model is based on the solution of mass exchange problem between a porous plate (frozen tissue) filled with a solid matter (ice) and an organic solvent (alcohol, acetone) that is contained in an apparatus with an active fluid circulation. The model takes in account porousness of tissue, dissolving of ice with solvent that produces a new medium, dissolving of that medium and its substitutions with solvent after solvent concentration exceeds evtectic concentration for the given temperature. Our results (fig. 1) agree with previously published results [1].

We also conducted experiments using original device [2] that implements freeze-substitution method. The device is made of the desk apparatus, comprising cryogenic and electron parts. Cryochamber ( Fig. 2 ) contains cylindrical unit (1), central channel (2) and located around it cylindrical vessels (3), connected by means of upper (4) and lower (5) channels with the central one. Perforated containers (6) with frozen bioobjects are adjusted on metal rack (7). The flux inducer (8) provides the circulation of substituting medium. The cold-conduct or (9) is submerged into a liquid nitrogen. Temperature control is performed be the thermogauge (10). The range of operating temperatures stabilization is from +20° to −120° C.

Type
Cryotechniques, Immunocytochemistry, and Electron Microscopy
Copyright
Copyright © Microscopy Society of America

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References

1.Humbel, B., Muller, M.. Proc. EUREM (1984) 1789.Google Scholar
2.Kaprelyants, A. S., Migunova, R. K.. Proc. Ann CRYO 98 Meeting (1998) 153.Google Scholar