INTERNATIONAL JOURNAL OF PHARMACEUTICS & DRUG ANALYSIS VOL.4 ISSUE 4, 2016; 183 – 187 ; http://ijpda.com ; ISSN: 2348-8948 183 REVIEW ARTICLE Tissue Fixatives: A Review Radhika Rai 1 , Amit Bhardwaj 2 , Shalu Verma 3 Department of Oral Pathology, FDS, SGT University, Gurgaon. Department of Periodontology, FDS, SGT University, Gurgaon. Department of Pedodontics and Preventive Dentistry, FDS, SGT University, Gurgaon. Date Received: 13 th April 2016; Date Accepted: 19 th April 2016 Date published: 22 nd April 2016 E-mail: nagpal.j@gmail.com Abstract: Fixation is the first or the foundation step of the histotechniques done to preserve the tissues in as close a life like state as possible by preventing their autolysis and putrefaction .A number of fixatives exists, either having being in use for decades, or in the case of formaldehyde over a century. Every fixative has different properties, each indicated for a special purpose based on the type of cell component to be studied, the method of sectioning and staining employed and the type of microscopy in- volved. Thus, a pathologist must have a fair idea of the properties of these commonly available fixatives, so that a correct choice can be made depending upon the desired results. This review aims to give a brief overview of the commonly available fixatives with their merits and their demerits. The fixatives discussed are: a formaldehyde containing fixative-10% Formalin, a picric acid fixative- Bouin’s Fluid, an alcoholic fixative- Clarke’s Fluid and a mercury chloride containing fixative- Zenker’s Fluid. Keywords: Bouin’s Fluid, Clarke’s Fluid, Tissue fixation, Fixative, Formalin, Zenker’s Fluid. Introduction: DIAGNOSIS’ [Greek: ‘dia’- through or by means of and ‘gnosis’ - knowledge] is the process of identifying and de- termining the nature and cause of a disease through com- plete evaluation of patient & review of the lab findings. Though the attempts to establish a confirmed diagnosis began since the days of Hippocrates, establishing a con- firmed diagnosis became possible only after the advent of histotechniques. Thus a proper fixation is mandatory to facilitate a correct diagnosis. ‘Histotechniques’ refer to the series of chemical proce- dures through which the tissues have to undergo before they are ready to be microscopically examined and diag- nosed 1 . Fixation is the first or the foundation step of the histotechniques and is done immediately after biopsy. Fixation is a complex series of chemical events which pre- serves the tissues in as close a life like state as possible by preventing their autolysis and putrefaction 1 . During this process, the semi fluid state of the cell is converted into a semisolid state thus maintaining, the morphology and structural details of the tissue 2 . The clarity of all microscopic preparations depends upon the adequacy with which the tissue is fixed. Faults of fixa- tion can not be remedied at any later stage and the fin- ished preparation can only be as good as the primary treatment. Thus a proper fixation is mandatory to facili- tate a correct diagnosis. To attain an ideal fixation it is not only essential to maintain the proper conditions but also to select an appropriate fixative 2,3 . There are many fixa- tives available. Though different fixatives have different features but there are certain features objectives which an ideal fixative must possess (Table I). In this review, fixatives with different chemicals as their base constituent have been reviewed and compared. The fixatives discussed are: a formaldehyde containing fixa- tive-10% Formalin, a picric acid fixative-Bouin’s Fluid, an alcoholic fixative- Clarke’s Fluid and a mercury chloride containing fixative- Zenker’s Fluid. Formalin Formaldehyde was discovered by Butlerov in 1859. It was first synthesized by Van Hoffman in 1868 who developed a practical method for its synthesis from methanol, and further established its properties thus establishing the practical aspects of its manufacture. Trillat in 1889 was the first to commercially manufacture formaldehyde as an industrial reagent after he was issued the patent, who in turn licensed several firms in France and Germany for its manufacture 4, 5 . Ferdinand Blum in 1892 discovered that formalin could serve to be an excellent fixative when he noticed that the skin of his fingers that had come in contact with the dilut- ed solution became hardened 5 . The molecular mechanism of tissue fixation by formalde- hyde is still not well understood. However the most pos-