Gelatin Adhesives
Gelatin is a protein and may be used as an adhesive. It is not as commonly used as albumen but can be effective, especially if treated with formaldehyde after the section is mounted. The formaldehyde fixes the gelatine in the same way as it does tissue proteins and makes a firm bond with them.
The formalin and ethanol in these methods fix the gelatin, which is in intimate contact with tissue proteins. The tissue is often very firmly held, and gelatin adhesion may be successful when egg albumen is not.
Haupt’s method may be used with frozen sections, particularly if used with formalin vapour for difficult tissues. Place a few drops of strong formalin into the bottom of a Coplin jar and put the slide in it for a time.
Formula
Solution A
| Material | Amount | |
|---|---|---|
| Gelatin | 0.01 | % |
Solution B
| Material | Amount | |
|---|---|---|
| Strong formalin | 20 | mL |
| 90% ethanol | 80 | mL |
Procedure
- Float sections onto warm gelatin (A) to flatten.
- Pick up and bake on as usual.
- Remove paraffin wax and bring to absolute ethanol as usual, then place into the alcoholic formalin (B).
- Determine the time by trial.
The gelatin may be made as a 5% stock solution, aliquoted in amounts needed to produce a final concentration of 0.01% in the waterbath (2 mL per litre), then refrigerated. Add one aliquot to the water in a tissue flotation bath and stir to distribute. Float out and pick up sections as usual. Replace the gelatin daily. Clean the waterbath daily to inhibit bacterial growth.
Safety Note
Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.
Solution A
| Material | Amount | |
|---|---|---|
| Gelatin | 1 | % |
Solution B
| Material | Amount | |
|---|---|---|
| Strong formalin | 20 | mL |
| 95% ethanol | 80 | mL |
Procedure
- Float sections onto warm gelatin (A) to flatten.
- Drain, and bake on as usual.
- Remove paraffin wax and bring to absolute ethanol as usual, then place into the alcoholic formalin (B) for 5 minutes.
- Transfer to 50% ethanol.
The gelatin should be fresh. A strong solution may be made as a stock and aliquoted into amounts suitable for daily use, then refrigerated. The aliquot may be diluted with warm water for use. Discard daily. Due to the concentration of the gelatin, this method may be more appropriate for individual slides heated on a warming plate rather than a tissue flotation bath.
Safety Note
Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.
Solution A
| Material | Amount | |
|---|---|---|
| Distilled water | 100 | mL |
| Gelatin | 1 | g |
| Glycerol | 15 | mL |
| Phenol | 2 | g |
Solution B
| Material | Amount | |
|---|---|---|
| Formalin, aqueous | 2 | % |
Procedure
- Dissolve the gelatin at 30°C and add the glycerol and phenol.
- Mix thoroughly.
- Smear a small amount onto a clean, grease free slide. These may be prepared ahead of time.
- Cover the gelatin on the slide with 2% formalin (B) and float sections onto it, warming to flatten.
- Drain and bake on as usual.
Adhesion may be increased by drying the section onto the slide in an atmosphere saturated with formalin vapor.
Safety Note
Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.
Due to the use of heat with formalin, this procedure should be done in a fume chamber or under a laminar flow hood.
References
- Gray, Peter. (1954)
The Microtomist’s Formulary and Guide.
Originally published by: The Blakiston Co.
Republished by: Robert E. Krieger Publishing Co.
Citing:
Moreau, (1918)
Bulletin de la Société mycologique de France
Paris, France.
And:
Langeron, M. (1942)
Précis de microscopie, ed. 6.
Paris, France. - Steedman, H.F., (1960)
Section cutting in microscopy
Blackwell Scientific Publications, Oxford, UK.
