What must be done during the dehydration step of the Pap stain procedure?

During the dehydration step of the Pap stain procedure, it is crucial to clear the slides in xylene. This step is essential because it serves to remove any excess alcohol that may be present on the slides after prior dehydration processes. Xylene is used as a clearing agent, which makes the tissue sections more transparent and helps to improve the staining quality by allowing the dye to penetrate better during the subsequent steps.

Using xylene also prepares the slides for infiltration with mounting media that is often a resin or a synthetic medium. If the slides are not cleared properly in xylene, the tissue might retain alcohol, interfering with the clarity and finish of the stained sample. The effectiveness of visualizing cellular structures in a Pap stain, which is critical for diagnosing conditions such as cervical cancer, relies heavily on proper processing during this step.