Improved Methods for Staining Fibrin

Abstract

Two methods used to demonstrate fibrin are the Fraser-Lendrum and Mallory's phosphotungstic acid-hematoxylin. One problem with the Fraser-Lendrum is that it requires the use of saturated alcoholic picric acid. To prepare this solution, a considerable amount of picric acid is required, which is an explosive. Federal and state regulations prohibit the storage of this chemical in the laboratory unless it is stored under water. We found that saturated aqueous picric acid could be substituted for the saturated alcoholic solution. Other changes were made to simplify the method. Mallory's method for fibrin requires treatment of tissue sections with potassium permanganate and oxalic prior to staining them with phosphotungstic acid-hematoxylin. We found that better staining results are obtained if the tissues are also treated with Zenker's fixative. However, Zenker's fixative contains mercuric chloride, a hazardous chemical that many laboratories have discontinued using. We found that zinc acetate can be substituted for mercuric chloride in preparing Zenker's fixative with excellent staining results when used in the Fraser-Lendrum and Mallory methods. (The J Histotechnol 26:127, 2003)Submitted April 10, 2003; Accepted April 22, 2003