Histologic Sectioning Produces TUNEL Reactivity

Abstract Objective.—To determine if the DNA strand breaks caused by tissue sectioning result in terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick end-labeling (TUNEL) reactivity. Methods.—The incidence and location of TUNEL-positive nuclei were determined in 5- and 15-μm sections of human stomach. Five- and 15-μm sections of tonsil were stained as a positive control. Results.—In 5-μm gastric sections, 69% of nuclei were labeled; in 15-μm sections, only 30% were labeled. In the latter sections, almost all labeled nuclei were located at the cut surface of sections. Labeled nuclei did not have apoptotic morphology. Apototic bodies and tingible body macrophages were labeled throughout 15-μm sections of tonsil. Conclusions.—Tissue sectioning creates TUNEL reactivity. The morphologic findings on routine stains should be considered the gold standard for the detection of apoptosis on tissue sections.