Biological freezing and cryofixation
- 1 September 1977
- journal article
- Published by Wiley in Journal of Microscopy
- Vol. 111 (1), 3-16
- https://doi.org/10.1111/j.1365-2818.1977.tb00042.x
Abstract
Freezing and freeze fixation are commonly used to achieve ultrastructural and biological preservation. Freezing in biological materials is complex because of their heterogeneous nature-water is unevenly distributed and the various domains are separated by semi-permeable membranes. Processes to be considered include: (1) osmotic gradients leading to redistribution of water, (2) nucleation and uncontrolled growth of ice crystals, (3) recrystallization of nucleated aqueous substrate. To avoid ultrastructural deformation in biological specimens cryofixatives are commonly employed. These are water soluble molecules, able to penetrate cell membranes (e.g. glycerol and dimethylsulphoxide). Interacting strongly with water, ions and bipolymers, they give rise to metabolic and physiological changes which render them useless for X-ray microprobe analytical studies. However, they can enable tissues to survive low temperature storage. Some plants and animals develop in vivo mechanisms which enable them to avoid or tolerate freezing. Alternative means of cryofixation have recently been developed. They rely on non-penetrating polymers of high and specific water binding capacity. These polymers enable the extracellular spaces to be vitrified rather than frozen. Such suppression of ice nuclei enables the cell contents to be maximally subcooled, resulting in the formation of nm dimension ice crystals. Since the polymers have a low osmotic activity and do not penetrate membranes, the interior of the cell is substantially undisturbed. Also hydrophilic polymers used as cryofixatives are physiologically less active than conventional cryoprotectants at equivalent weight concentrations, and th eir mechanical properties render them useful as matrices for cryosectioning.Keywords
This publication has 57 references indexed in Scilit:
- Polymeric cryoproteetants in the preservation of biological ultrastructureJournal of Microscopy, 1977
- Polymeric cryoproteetants in the preservation of biological ultrastructureJournal of Microscopy, 1977
- Cold Hardiness and Deep Supercooling in Xylem of Shagbark HickoryPlant Physiology, 1977
- The Thermodynamics of Water Transport From Biological Cells During FreezingJournal of Heat Transfer, 1975
- Nuclear Magnetic Resonance of Water in Cold Acclimating Red Osier Dogwood StemPlant Physiology, 1974
- Membrane structure and electron microscropy the significance of physical problems and techniques (freeze etching)Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, 1972
- Recent progress in the freeze-etching techniquePhilosophical Transactions of the Royal Society of London. B, Biological Sciences, 1971
- Nuclear spin relaxation and self-diffusion in the binary system, dimethylsulphoxide (DMSO)+ waterTransactions of the Faraday Society, 1971
- Interactions of Cooling Rate, Warming Rate and Protective Additive on the Survival of Frozen Mammalian CellsPublished by Wiley ,1970
- The low Temperature Denaturation of Chymotrypsinogen in Aqueous Solution and in Frozen Aqueous SolutionPublished by Wiley ,1970