Comparing the Decay Rates of Cardiac and Renal Tissues: A Histo-Taphonomical Approach in Estimating Postmortem Interval Using Swine Models

Abstract

Introduction: Predicting the time of death is one of the focal things when carrying out medico-legal investigations.

Aim: This study investigated the histo-taphonomic decomposition rates between the heart and kidney using porcine models for the estimation of post-mortem interval (PMI).

Methods: This study comprised of sixteen (16) healthy male pigs (Sus scrofa domestica) euthanized using cervical blunt force trauma. The tissues were eviscerated and kept in an enclosed building for a period of 5 days. The tissues were obtained at varied post-mortem intervals of 0, 2, 6 and 10 hours respectively for day one, day two to five, tissues were taken three times daily (morning, afternoon and evenings) 102 hours after death. Fixed in Bouin’s fluid for 6hours and transferred to 70% ethanol, the tissues were further processed and stained with H&E and viewed in a light microscope of 100x magnification.

Results: These results showed that between 0 to 6 hours, the heart had normal cardiomyocytes. By 10 hours, separation of cardiomyocytes, gradual shrunken nuclei, and sparse areas of vacuolated myocytes and interstitial edema.  Followed by myofiber waviness, edema, early eosinophilia, pyknosis of myocardia nuclei and fibrocyte and neutrophilic influx after 18 hours. Between 24-102 hours, the heart showed coagulative necrosis of myocyte nuclei, neutrophilic influx and continuous shrunken nuclei. Meanwhile, the kidney between 0-2hours showed normal renal micro-architecture but after 6-hours, chromatin condensation, shrunken nuclear proximal convoluted tubules and the distal convoluted tubules cellular swelling and cytoplasmic dissolution in distal convoluted tubules and followed between 10-18 Hours:  anucleations, cellular ruptured bowman’s space, cellular detachment, overall sloughing which persisted from 24 hours to 102 with increasing severity.

Conclusion: These findings showed more rapid decomposition rate in kidney compared to the heart, which makes organ-specific analyses a must in taphonomic casework for the accurate estimation of PMI.