CHAPTER 13 - PARAFFIN WAX TECHNIQUE

Abstract

This chapter reviews paraffin wax technique. The original fixative solutions used are not miscible with paraffin wax and therefore, preliminary dehydration is necessary. The three solutions commonly used for this purpose are alcohol, acetone, and dioxane. The alcohol method consists in passing the tissue through a series of progressively more concentrated alcohol baths. The acetone method is used for the most urgent biopsies. Dioxane is a unique reagent with the unusual property of being miscible with both water and molten paraffin wax. Dioxane should be used only in a well-ventilated laboratory, and any residues should be washed down the sink. Clearing or dealcoholization is the term applied to removal of alcohol from blocks or sections of tissue, which usually acquire a transparent appearance in the process. The chapter also discusses the process of impregnation with paraffin wax. Automatic tissue processers, which are rapidly becoming standard equipment in histological laboratories, require the minimum of supervision. The vacuum-embedding technique depends on the production of negative pressure inside the embedding oven.