Cryofixation Without Pretreatment at Ambient Pressure

摘要: Almost a century ago biological or medical objects were used in their frozen state order to accelerate pathological diagnosis (immediate section) and better maintain chemical constitution (Altmann 1890). This alternative fixation gained importance during the first half of this due availability liquefied air as coolant (“cryogen”) well fact that effective cooling systems for cryostats had been developed (see e.g. Gersh 1932; Simpson 1941; Eranko 1954; Kulenkampff 1955; Neumann 1958). Attempts freeze wet electron microscopy revealed at normal atmospheric pressure under most favourable conditions only an approx. 30- μm border zone can be perfectly Sitte 1979; Plattner Bachmann 1982; Robards Sleytr 1985). At greater depths mixed plasmatic phases segregate. The size these segregation compartments formed by growing ice crystals within specimen increases so rapidly deeper layers cannot microscopy. depth well-preserved increased without pretreatment to, most, 300 applying high pressures about 2100 bar (Muller Moor 1984). These limits considerably extended use anti-freezing agents (“cryoprotectants”): glycerol has proved anti-freeze freeze-fracture/freeze-etch method (Moor Muhlethaler 1963) saccharose cryoultramicrotomy Bernhard Leduc 1967; Tokuyasu 1973; Griffiths et al.