2016 Volume 65 Issue 1 Pages 78-83
It is difficult to distinguish clearly the color contrast between the cytoplasm and collagen fibers by collagen fiber staining methods such as AZAN staining if tissues are treated only with formalin. To settle this, a mordant with a mixture of equal amounts of 10% potassium dichromate and 10% trichloroacetic acid was considered, and it is generally utilized at present. However, it is necessary to develop a substitute mordant because potassium dichromate is a hazardous reagent. Thus, we examined the usefulness of other mordants in AZAN staining. As a result, we were able to clearly distinguish between the cytoplasm and collagen fibers when we used Bouin’s fluid or only a picric acid-saturated aqueous solution as the mordant. Bouin’s fluid includes formalin, which is regulated by the Ordinance on Prevention of Hazards due to Specified Chemical Substances, and has the problem of being a chemical hazard. Therefore, in AZAN staining, the use of picric acid at 60°C for 30 min may replace the traditional use of a mixture of equal amounts of 10% potassium dichromate and 10% trichloroacetic acid. Moreover, the widespread use of this method is desired because it is safer and shows better stainability.
