IMVS Division of Pathology
The Queen Elizabeth Hospital
Woodville Road, Woodville, South Australia 5011
Drying out of the specimen before fixation which is a form of mummification. This usually occurs in the theatre where the specimen can be left for some minutes before being placed into fixative. Drying out of the specimen and the beginnings of autolysis and putrefaction can occur all of which can have a bearing on the H&E.
The fixative. Is your fixative a fixative? Who made it up? Is it made up correctly? Even commercial organisations have been known to produce bad batches of fixatives and dye solutions. If the fixative is not as it should be it too can affect the H&E.
Poor staining is most often seen in small biopsies and it is almost always due to over-processing – using long processing schedules when very short schedules should be used. Over-processing causes other problems as well such as sections can be difficult to obtain because of hard, brittle tissue.
Re-cyclers do not produce absolutely pure 100% ethanol. There is always a little water left behind. So if this re-cycled product is used as absolute ethanol there will be too much water retained in the tissue which will affect subsequent processing and staining. Re-cycled ethanol should only be used as a 95% ethanol.
The slides should only be dried at just above the melting point of the wax. At over 70 degrees C the tissue starts to cook, which alters the tissue characteristics and usually results in dark smudgy staining.
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© Roy C. Ellis 2002