Comparison of Formalin Fixation and Formalin Substitute Fixatives in Histopathology Laboratories

Abstract

This comparative study was carried out in a lab animal (rabbit)during the period from June 2007 to September 2007 . The study aimed to compare between formalin as a routine fixative used in histopathology laboratories and some formalin substitute fixatives . Three groups of fixatives are used . This include aldehyde based fixatives ( e.g. 10%formalin ) , alcohol based fixatives ( e.g. Omnifix ) and physical fixative (e.g. microwave irradiation (MW) ) . 120 biopsies were obtained from rabbit . Of these , 30 biopsies were fixed by formalin , 30 by omnifix and the remaining 60 were fixed by microwave for 3min and 5 min . After tissue processing , all sections were stained with H&E to compare between effect of the fixation on the feature of nuclear chromatin patterns , cytoplasmic details and the background staining . Four different histochemical techniques ( silver impregnation technique , Periodic Acid Schiff's (PAS) , Alcian blue and Perl's Prussian blue technique) were performed to certain type of the tissue . In addition immunohistochemistry stain were performed to show the antigen reactivity on some organs. Our findings indicated that both formalin substitutes used in this study (MW and Omnifix ) showed well preservation of the nuclear details , cytoplasm appearance and tissue architecture and well immunoreactivity . On the other hand the microwave fixation reduced the time .We concluded that both MW and Omnifix were provide adequate fixation for tissue specimens as the same as formalin . Therefore , we recommended substitution of formalin in our laboratories to provide a healthy environment and to avoid formalin carcinogenicity .