Several solutions are possible for the conservation of interesting specimens. The simplest consists in adding an equal amount of glycerol or propylene glycol to the sediment volume. The resulting solution is kept at -20C. This mixture preserves the elements for a certain time, but cellular degradation is rapid.
Conservative media
Sediments can be kept refrigerated in Hank's solution, with added antibiotics. The antibiotics used can be the same as those used for cell culture. We are using streptomycin with a 1g/L concentration. Nystatin should be added to prevent yeast growth.
Method
- 10 mL of Hank's solution is added to the sediment.
- The mix is centrifuged.
- The added volume is aspirated.
Conservation times vary with the element and the type of examination. Cast's general picture is preserved for weeks. Cells are preserved only a few days. Cell degradation is seen as many types of vacuolisation, rendering identification almost impossible. For PAP staining, cell characteristics not noticeable on a wet preparation are preserved for only a few hours.