We have some brain samples that were not fixed prior to freezing, making sectioning and mounting very difficult. Has anyone had any success with thawing a frozen brain so that it can be drop-fixed?
An old 'technique' in (diagnostic) Pathology is to drop (previously for rapid diagnostic cryosectioning) frozen (biopsy) samples into (P)FA-(generally aldehyde) solution as a fixative for further processing, embedding into paraffin and further section evaluation .
Naturally, the quality of morphological preservation will be impaired.... but IMHO that will depend also on further circumstances [e.g. like: former freezing parameters (i. e. tissue type, size of the specimen, pretreatment if any, freezing conditions: 'rapid' freezing by CO2, shock-freezing by / in pre-cooled isobutanol or even liquid nitrogen /LN-slush, etc., storage -25° C, -80°C). If the freezing process of suitable specimens was NOT suboptimal at least part of the specimens might be used for general purposes or even IHC if you carefully have trimmed away OCT-compound and drop the unfixed, frozen specimen left into pre-chilled (and further maintained at low temperature, which might be nearly at or even below 0°C ) buffered fix-solution (which, as you know might also be an alcoholic fixative, which could be chilled to minus 10° or to -minus 25°C). If that is a solution to your 'problem' or compatible with your examination task therefore depends.... But always worth a try.... Best wishes and good luck W.M.
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