Elevated Pressure Improves the Rate of Formalin Penetration while Preserving Tissue Morphology

Ingrid E. Chesnick¹, Jeffrey T. Mason¹, Timothy J. O'Leary², Carol B. Fowler^1,2 ^✉

1. Department of Biophysics, Armed Forces Institute of Pathology, Rockville, Maryland, USA;
2. Biomedical Laboratory Research and Development Service, Veterans Health Administration, Washington, DC, USA

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Citation:
Chesnick IE, Mason JT, O'Leary TJ, Fowler CB. Elevated Pressure Improves the Rate of Formalin Penetration while Preserving Tissue Morphology. J Cancer 2010; 1:178-183. doi:10.7150/jca.1.178. Available from http://www.jcancer.org/v01p0178.htm

Abstract

Formaldehyde fixation and paraffin-embedding remains the most widely used technique for processing cancer tissue specimens for pathologic examination, the study of tissue morphology, and archival preservation. However, formaldehyde penetration and fixation is a slow process, requiring a minimum of 15 hr for routine processing of pathology samples. Routinely fixed samples often have a well-fixed outer rim, with a poorly-fixed inner core of tissue. In this study, we show that the application of elevated pressure up to 15,000 psi improves the rate of formaldehyde fixation by approximately 5 to 7-fold while preserving the tissue morphology of porcine liver. The tissue also exhibited much more uniform formaldehyde penetration after 30-60 min incubation under elevated pressure than samples fixed for the same length of time at atmospheric pressure.

Keywords: FFPE, fixation rate, formalin-fixed paraffin-embedded, high-pressure, histology