The following steps are performed after sectioning tissue samples that have been processed in the routine manner (paraffin) and placing them on the microscope slides:
1. Deparaffinization (usually a two step process):
- First, the slides are placed in a drying oven to remove the water from the tissue, help adhere the section to the slide, and start removing the wax from around the tissue.
- Then, the slides are brought through 2-3 changes of a clearing agent such as xylene which removes the remaining paraffin from the slides and tissue so that the dyes can then penetrate into the cells.
2. Hydration: This is accomplished by using a series of graded alcohols to reintroduce water to the tissue. It begins as the slides go through absolute alcohol which removes the clearing agent. Then they go through several changes of lower percentage alcohols until they reach water. This is a necessary process which prepares the tissue to stain with the aqueous staining solution.
