Elemental concentrations in air-exposed and vacuum-stored cryosections of rat liver cells

Elemental concentrations in different compartments of cryosections of isolated rat liver cells cryotransferred and freeze-dried were compared with those obtained after storage under vacuum for 12 or 60 h and after exposure to room air for 2 min. Poorer image contrast and segregation artefacts are frequently found in air-exposed sections, together with a slight but significant decrease of the K concentration in the cytoplasm and an increase of the S concentration in the liver cell nuclei and the extracellular medium. Extreme distortions of both ultrastructure and elemental distributions are observed if the sections are even slightly colder than the surrounding atmosphere. While storage of frozen-dried cryosections under vacuum for less than 12 h does not lead to alterations in the sections, gross changes are found both in morphology and elemental distribution in sections stored under vacuum for about 60 h. Long-time vacuum storage of frozen-dried cryosections is, therefore, not recommended.