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Helly’s Fluid

Helly’s Fluid

Formula

Stock Helly’s base

MaterialAmount
Mercuric chloride49.2g
Potassium dichromate20g
Sodium sulphate10g
Distilled water960mL

Working Helly’s solution

MaterialAmount
Stock Helly base48mL
Formalin, concentrated2.5mL

Make just before use.

Description

This is a good routine fixative giving excellent cytoplasmic preservation, although it is not used as much as it was in the past due to the mercuric chloride content.

It should be noted that the stock Helly’s base solution is identical to that of the stock Zenker’s base solution and is a fixative in its own right, giving good cytoplasmic preservation.

Time

Small, thin, pieces of tissue will be fixed in a few hours. Three millimeter thick slices will require overnight.

Aftertreatment

Wash well with running tap water to remove excess dichromate. Treat sections with the iodine thiosulphate sequence to remove mercury pigment.

Due to its mercuric chloride content this fixative will corrode metal. Metal cassettes, metal jar lids, metal forceps, metal rulers, metal countertops and all other metal objects must be avoided. This includes stainless steel, which may resist corrosion better than other metals but will still be affected. Dry paper towels are an effective barrier. Do not forget to dispose of them safely.

Safety Note

Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.

References

  1. Gray, Peter. (1954)
    The Microtomist’s Formulary and Guide.
    Originally published by: The Blakiston Co.
    Republished by: Robert E. Krieger Publishing Co.
    Citing:
    Helly, (1903)
    Zietschrift für wissenschaftliche Mikroskopie und für mikroskopische Technik, Leipzig

Most reference texts contain a variant of this solution under the Helly name, although the amount of each ingredient may be slightly different.