What is the primary purpose of clearing in histotechnology?

The primary purpose of clearing in histotechnology is the removal of alcohol from tissue. In the process of tissue preparation for histological examination, tissues are initially fixed in formalin or other fixatives and then dehydrated using increasing concentrations of alcohol. The clearing step follows dehydration and involves treating the tissues with a clearing agent, such as xylene, which removes the alcohol. This is essential because it allows the tissues to become transparent and prepares them for embedding in paraffin wax, which is the next step in sample processing.

Once the alcohol is removed, the tissues can be infiltrated with paraffin wax, which provides support for the tissue structure when sections are cut for microscopy. This is crucial for ensuring that the cellular details are preserved and visible for diagnostic purposes. Without proper clearing, the embedding medium would not adequately infiltrate the tissue, leading to poor quality sections and subsequent analysis.