A Convenient, Permanent Slide Mounting Medium

(From: 1983. Mycological Society of America Newsletter 34(2):59)

Preservation of slide mouts of fungi is a common problem for many Mycologists. A mounting medium ("PVLG") described by Omar et. al. (1979) has been very effective in our laboratories, but does not appear to gave wide usage by U.S. Mycologists.

The ingredients are:
polyvinyl alcohol 8.33g
distilled water 50mL
lactic acid 5mL
glycerine 5mL

Several types of polyvinyl alcohol (PVA) are available, but only those with high viscosity form permanent mounts. We recommend those types with a viscosity of 24-32 centipoise (available from Fisher or other scientific supply houses for a modest price). PVA with a lower viscosity will not harden sufficiently for long-lasting slides.

To prepare PVLG, add the polyvinyl alcohol (a dry powder) to the water and put in 60 degree oven until dissolves. Add lactic acid and glycerine and allow the solution to set for 24 hours before first using. Specimens can be mounted directly in the PVA solution, or the solution can be added to the sides of the cover slips that were made with water, lactophenol, or melzer's reagent. The PVA solution will infiltrate the material in a day or two. Slides made with PVLG can be hardened by heating at 40-75oC overnight. Immersion oil can be wiped from these hardened slides without disturbing the specimen.

REFERENCES

R.E. KOSKE, Department of Botany
Bruce Tessier, Department of Plant Pathology an d Entomology
University of Rhode Island
Reference: Omar, M.B., L. Bolland, and W.A. Heather. 1979. A permanent mounting medium for fungi. Bull. Brit. Mycol. Soc. 13:31-32