ABSTRACT
Mounting media differ according to whether they are used to mount stained or unstained tissues. Some media are less suited for particular stains than others because they allow stains to fade or leach out of the preparation. Similarly, stains and dyes should not dissolve into the mountant. Preparations are dehydrated and passed through transition or clearing fluids before mounting in media which are water-immiscible. Mounting preparations from xylene, or other transition media must be done in a fume hood, and the slides left in the fume hood to dry before being labelled and hardened permanently in a 40°C oven for a few days prior to storage in a slide cabinet. All coloured preparations undergo fading with time. This results in loss of contrast, and is often irreversible.
