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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
Wrinkles appearing in sections floated on a flotation bath. There’s nothing worse than cutting a great, flat, smooth section and then floating it onto the water bath and finding it full of wrinkles.
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This can be caused by the Flotation bath being too cold. If the water is too cold the wax surrounding the section will not expand and flatten. And it is the expansion and flattening of the wax which also flattens the section, if it is properly infiltrated with wax. Ideally the flotation bath should be kept at temperature about 5°C below the melting point of the wax being used.
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Or the Knife is too blunt (especially if wrinkles are in the vertical plane)
This is a section of endometrium stained Haematoxylin and Eosin and showing wrinkles in the vertical plane. In this section the wrinkles in the vertical plane are caused by a blunt knife which tends to stretch tissue as it cuts rather than passing smoothly through the tissue, whilst the wax, being soft, cuts quite well. So you end up with smooth wax but stretched tissue. When that is floated onto warm water the wax smooths out nice and flat but leaves the tissue wrinkled. Those wrinkles are very hard to remove. Leaving a section on the water bath for a long time, until the wax begins to expand will sometimes allow you to flatten the section, but not always. The best solution is to use a sharp knife in the first place.
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© Roy C. Ellis 2002