Paraffin embedding of biopsy specimens is an old and simple technique which presents many advantages, particularly the cutting of thin sections. Since paraffin is immiscible with water, tissues must be thoroughly dehydrated prior to embedding. The compound generally chosen for this purpose is ethyl alcohol in graded concentrations. Paraffin, however, is also immiscible with the usual dehydrating agents. Therefore, an intermediary substance miscible with both the dehydrating agent and paraffin must be used, and it is this compound—usually chloroform or benzene— which has been termed the "clearing agent."1 In the past, dioxane (diethylene dioxide), which is miscible with paraffin, has been used to dehydrate specimens. Unfortunately, the vapors of this compound are toxic, and dioxane has been largely abandoned as a dehydrating agent. The chemically related compound, tetrahydrofuran, is, however, completely miscible with paraffin and water in all proportions, and it has not been reported to be toxic
MALKINSON FD, POTTER B. Use of Tetrahydrofuran for Routine and Rapid Dehydration and Clearing. Arch Dermatol. 1960;82(5):798–803. doi:10.1001/archderm.1960.01580050140021
Customize your JAMA Network experience by selecting one or more topics from the list below.
Create a personal account or sign in to: