Flammable substances are integral to histological techniques for several reasons: 1. Solvents: Chemicals like ethanol and xylene are used for dehydrating and clearing tissues. 2. Fixatives: Formaldehyde, a flammable fixative, preserves tissue morphology. 3. Stains: Many staining reagents contain alcohols or other flammable solvents that are essential for visualizing tissue structures under a microscope.