Dehydration, Impregnation and Embedding Techniques

This chapter discusses dehydration, impregnation, and embedding techniques. It describes paraffin wax technique. The original fixative solutions used are not miscible with paraffin wax, therefore preliminary dehydration is necessary. The three solutions commonly used for this purpose are alcohol, acetone, and dioxane. Clearing'or de-alcoholization'is the term applied to the removal of alcohol from blocks or sections of tissue by immersing them in an ante-medium. Clearing agents must be miscible with both alcohol and paraffin wax. The most common clearing agents are xylene, toluene, chloroform, and cedar wood oil.. The chapter also describes vacuum-impregnation techniques. The vacuum-impregnation technique depends on the production of negative pressure inside the embedding oven. This pressure reduction hastens the extrusion of air-bubbles and of the clearing agent from the tissue-block, facilitating rapid penetration by the wax. A variety of moulds is available for blocking out or embedding the tissue in paraffin wax.