In order to get detailed histological data of the brain high-quality histological sections and reliable histological processing must be done. There are a few steps in a process of preparation tissue before sectioning:
• Fixation - (formaldehyde and formalin are the most commonly used fixatives). This step is necessary to preserve the tissue sample in a state as close to that during life.
• Dehydration - by using high concentrations of alcohol ( 60% ethanol in water) Ths step is for removing excess fluid.
• Clearing – (xyrene, benzene , chloroform) Process of removing the dehydrating agent.
• Embedding (paraffin) The step of putting the tissue in a medium to allow thin slices to be cut cleanly. It provides rigid support to the tissue.