Tissue processing involves treating tissues to impregnate them with a solid material like paraffin wax to facilitate microscopic sectioning. Proper identification, fixation, and any special post-fixation treatment is important. The goal of tissue processing is to embed tissues in a solid media for support, rigidity for sectioning, and minimal damage. Key steps are completion of fixation, dehydration, clearing, and embedding. Factors like agitation, heat, viscosity, ultrasonic, and vacuum can affect the rate of fluid penetration and impregnation during processing.