What is the first step in the dehydration sequence for Zenker's fluid?

The first step in the dehydration sequence for specimens fixed in Zenker's fluid involves placing the tissue in running water for a period of time, typically ranging from 1 to 12 hours. This initial step is crucial for removing excess fixative from the tissue to prevent interference with subsequent processing steps. Running water helps to wash away the mercury present in Zenker's fluid, which is important for both tissue clarity and safe handling.

Starting with this washing step is essential for preparing the tissue adequately for dehydration, as it prepares the specimen for a sequence of alcohol baths that will effectively remove water from the tissue. The subsequent stages of dehydration (using alcohol at various concentrations) depend on the successful removal of the fixative to ensure optimal tissue preservation and integrity throughout the histological processing.