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Problems in Histopathological Technique
Prepared by
ROY ELLIS
IMVS Division of Pathology
The Queen Elizabeth Hospital
Woodville Road, Woodville, South Australia 5011
Email: roy.ellis@imvs.sa.gov.au
Cells in stained tissue sections appear crenated
This is a section of kidney stained Haematoxylin and Eosin showing crenation in cells and overstaining with eosin. The eosin definitely lacks differentiation.
Cause?
This effect is
caused by hypertonic solutions resulting in water flow from the cell
into the fixative solution during fixation. Its a difference in
osmolarity between the tissue and the fixative. Osmolarity of
fixatives needs to be balanced to that of the tissue being
preserved. Its best to use an isotonic fixative solution which
exerts the same osmotic pressure as the cells in tissue, in other
words a fixative made up in physiological saline such as a buffered
formol saline or neutral buffered formalin.
Solution
The best average is achieved with aqueous fixatives, not alcoholic, buffered to a neutral pH. In fact the effect of crenation is seen more markedly with fixatives which contain alcohols, like Carnoy’s and is sometimes observed in cytology preparations when absolute alcohol, absolute isopropanol or methanol are used as the fixative. Better osmolarity is achieved by using 80 to 95% ethanol, 60% isopropanol or 95% methanol. There will still be some shrinkage of cellular material, but the crenated effect is avoided.
This is also a section of kidney stained H&E but showing well rounded, well preserved nuclei and with differential eosin staining.
Just as it should be after fixation in neutral buffered formalin.
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© Roy C. Ellis 2002