As the first stage of a multistep process to prepare surgical specimens for microscopic analysis, tissue fixation must demonstrate the ability to preserve the architectural and morphologic integrity of cells and their supporting matrix.  Additional criteria for an effective fixative medium includes the ability to withstand the treatments involved in all steps associated with tissue preparation, including specimen transport, and the processing steps that encompass tissue dehydration, embedding, microtomy and staining.  For specialized techniques, such as immunohistochemistry, an effective fixative must also demonstrate the ability to retain tissue antigenicity such that the subsequent steps of antigen retrieval can be optimally executed.
Currently, 10% neutral buffered formalin serves as the gold standard for fixation of tissue in preparation for routine histologic, histochemical, and immunohistochemical assessments.  However, as a non-viscous liquid preparation, it is prone to leakage during transport of pre-filled specimen containers, thus posing potential hazards for laboratory couriers, as well as for commercial ground and air transportation carriers.  Additionally, in a liquid form, volatility of the substance is high, and this may further increase the health hazards to laboratory personnel.
To address these concerns, a 10% formalin gel preparation (Formagel) was formulated by Azer Scientific, Inc. (Morgantown, PA) as a substitute to the traditional liquid based, 10% neutral buffered formalin.  This formalin preparation is more viscous, less prone to leakage in prefilled specimen containers, and has less volatility as a mucosal irritant.  Validation testing performed by two independent laboratories (LaFriniere and Lu, unpublished data) has demonstrated equal efficacy between Formagel and 10% neutral buffered formalin with respect to hematoxylin uptake, eosin uptake, cellular preservation and detail, staining as well as background cleanliness.
This study attempts to additionally characterize the efficacy of Formagel as a fixative for the purpose of immunohistochemistry, an important and commonly employed technique in modern anatomic pathology.
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