ORIGINAL RESEARCH article

Front. Vet. Sci.

Sec. Veterinary Clinical, Anatomical, and Comparative Pathology

Volume 12 - 2025 | doi: 10.3389/fvets.2025.1578579

This article is part of the Research TopicAdvances in non-clinical and translational studies: cutting-edge study designs, special technologies, routine pitfalls, background findings and control data.View all 8 articles

Onset and Progression of Postmortem Histological Changes in the Kidneys of RccHan TM :WIST Rats

Provisionally accepted
Ricardo  De MiguelRicardo De Miguel1*Raquel  VallejoRaquel Vallejo1Kristel  KeglerKristel Kegler1Robert  KreutzerRobert Kreutzer1Francisco  José MayoralFrancisco José Mayoral2Yoshimasa  OkazakiYoshimasa Okazaki1Paula  OrtegaPaula Ortega1Laura  PolledoLaura Polledo1Tanja  RazingerTanja Razinger1Olivia  Kristina RichardOlivia Kristina Richard1Raúl  SanchezRaúl Sanchez2Nils  WarfvingNils Warfving1Anna  DomènechAnna Domènech2Klaus  WeberKlaus Weber1*
  • 1AnaPath Services GmbH, Liestal, Switzerland
  • 2AnaPath GmbH, Liestal, Switzerland

The final, formatted version of the article will be published soon.

Death initiates a cascade of physiological and biochemical alterations in organs and tissues, resulting in microscopic changes that challenge the histopathological evaluation. The aim of this study was to compile and illustrate the microscopic changes in the kidneys of rats subjected to delayed postmortem fixation. It also scrutinizes the influence of exsanguination, cooling methods and air circulation on the initiation and progression of these alterations. Twenty-four Wistar Han outbred rats (RccHan TM :WIST) were sacrificed and stored either at room temperature (18-22 ºC; half of the carcasses were exsanguinated after sacrifice) or under refrigeration (2-4 ºC). Necropsies were conducted at different time points postmortem (i.e., 0.5h, 1h, 4h, 8h, 12h, 24h, 36h, 48h for carcasses stored at room temperature, and 7 days and 14 days for carcasses stored under refrigeration). Kidney sections underwent simultaneous digital evaluation by 14 pathologists until a consensus was reached on the key findings, terminology and intensity levels. When stored at room temperature, the first changes were seen after 4 hours, and involved distal convoluted tubules and inner stripe of the outer medulla. After 8 hours, all structures except glomeruli were affected. Alterations were similar in quality and intensity after 36 hours as after 48 hours. Exsanguination delayed the onset of postmortem changes and slightly decreased their overall severity at any given timepoint. The nature of the changes under refrigeration was like those alterations noted in animals stored at room temperature. The intensity of postmortem changes observed after 7 and 14 days under refrigeration was similar to those recorded after 48h at room temperature. No clear differences were observed between animals stored in a closed plastic bag and animals stored in a perforated carboard box to allow air circulation. This work elucidates the onset and progression of postmortem changes in the kidneys of Wistar Han rats, offering insights to accurately differentiate them from real changes and enhance histopathological evaluation.

Keywords: Autolysis, postmortem, rat, artifact, Delayed fixation, decomposition, Kidney, Histology KW

Received: 17 Feb 2025; Accepted: 31 Mar 2025.

Copyright: © 2025 De Miguel, Vallejo, Kegler, Kreutzer, Mayoral, Okazaki, Ortega, Polledo, Razinger, Richard, Sanchez, Warfving, Domènech and Weber. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Ricardo De Miguel, AnaPath Services GmbH, Liestal, Switzerland
Klaus Weber, AnaPath Services GmbH, Liestal, Switzerland

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