The commonly used dehydrants in tissue processing are: Ethanol*: This is the most widely used dehydrant due to its effectiveness, relatively low cost, and safety. It is used in a graded series of concentrations, starting from lower percentages (e.g., 70%) and progressing to absolute (100%) ethanol. Isopropanol*: Another effective dehydrant, often used as an alternative to ethanol, especially for certain types of tissues or when cost is a major consideration. Acetone*: A fast-acting dehydrant that can be used at room temperature. However, it can cause some shrinkage and distortion of tissues if not used carefully. Methanol*: Less commonly used for routine tissue processing compared to ethanol, but it can be effective.