IMVS Division of Pathology
The Queen Elizabeth Hospital
Woodville Road, Woodville, South Australia 5011
Recovering tissue that has dried out after a malfunction of a tissue processor. Depending upon where in the cycle the malfunction occurred tissues can become almost mummified, very hard and rubbery.
One solution is to place dried out tissue into a formol-glycerol solution for 5 to 10 hours, depending upon the size of the block. The time is not critical because extended exposure in the solution will not harm tissues.
The stock solution contains
10 ml formaldehyde
2 gm sodium acetate
and 90 ml tap water.
To produce a working solution from the stock solution 10 ml glycerol is added to 90 ml of the formol-sodium acetate.
After treatment tissues can be returned to a tissue processor at the dehydration stage of a schedule. This method can also be used for softening any dried or hard specimen as formol-glycerol is quite a good softening agent.
The solution was originally developed to soften mummified tissue from Egyptian tombs and we have used it successfully on tissues which dried out during a processor malfunction before the age of enclosed processors. Enclosed processors tend to keep tissues moist so this problem is less commonly seen nowadays.
A section from Kidney and stained with Haematoxylin and Eosin after 5 hours recovery
A section of Kidney stained with Haematoxylin and Eosin after 10 hours recovery fluid
If the sections are compared – the gaps in the tissue are still present but the nuclei have recovered after 10 hours treatment and staining is improved although the cytoplasm is staining very red in both sections with virtually no diffrentiation of the eosin. But at least the tissue can be identified and a diagnosis made.