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Abstract
Optimal tissue preservation is critical in histotechnology to ensure quality of hematoxylin and eosin (H&E)-stained sections and enable light microscopic assessment by pathologists. Direct immersion of tissues in 10% neutral buffered formalin is the routine practice in histopathology laboratories, but whole body perfusion techniques are occasionally used, especially when high-quality tissue samples are required. The objectives of this study were to evaluate the impact four different whole body perfusion techniques have on preserving H&E tissue quality and cellular morphology using light microscopy and immunohistochemistry. Four different rat whole body perfusion techniques were conducted and compared: (1) physiological saline at pH 7; (2) physiological saline at pH 7 with heparin; (3) 4% paraformaldehyde fixative; and (4) physiological saline at pH 7 with heparin followed by 4% paraformaldehyde. All solutions were chilled prior to the start of the perfusion. Furthermore, alpha-smooth muscle actin (αSMA) immunohistochemistry was employed to investigate the effects of these techniques on tissue antigenicity. Light microscopic examination and comparison of brain, kidney, and pancreas tissues revealed no differences in cellular (nuclear or cytoplasmic) morphology among the four different perfusion techniques. In the liver, a more distinct hepatic cord pattern was noted in groups 1 and 4 compared with groups 2 and 3, with group 2 showing the least distinctive hepatic cord pattern. In addition, a noticeably more prominent vascular congestion was noted in group 3 compared with other groups. Furthermore, more artifactual vacuolation was noted in the brain in group 3 compared with other groups. No differences in αSMA immunorecognition were noted by immunohistochemistry. In conclusion, different whole body perfusion can have an impact on hepatic morphology, presence of vascular congestion, and artifactual vacuolation in the brain. The utility of any of the perfusion techniques should be considered on a case-by-case basis depending on the scientific question being answered.