The Forensic Spleen and Lungs: Comparing the Histo-taphonomy of Porcine Structures in Postmortem Interval Estimation

Accurate determination of the postmortem interval (PMI) remains problematic in forensic investigations due to the complexity of biological and environmental factors that influence tissue decomposition. This study conducted a comparative histotaphonomic analysis of splenic and pulmonary tissues in porcine models to evaluate their reliability as biological indicators for PMI estimation. Sixteen (16) healthy domestic pigs (Sus scrofa domestica) were humanely euthanized, and spleen and lung tissues were harvested and maintained under specified conditions to decompose over five days. Tissue samples were collected at 0, 2, 6, and 10 hours postmortem on Day 1, and daily from Days 2 to 5, fixed in Bouin’s solution, and stained using histological assessment performed using Hematoxylin–Eosin (H&E) and Masson’s Trichrome (MT). At 0–2 hours postmortem, the spleen showed intact white and red pulps, while the lungs showed well-defined alveolar sacs and bronchioles. Early autolytic changes, including nuclear shrinkage and mild structural disorganization, appeared by 6–10 hours. By Day 2, both organs demonstrated marked cellular degradation, with the spleen showing nuclear loss and matrix disorganization and the lungs exhibiting alveolar collapse and epithelial pyknosis. MT staining revealed progressive collagen degradation and connective tissue atrophy from Day 3 onward, with more pronounced changes in the lungs. By Day 5, both organs showed advanced decomposition with complete architectural collapse. Overall, the lungs decomposed faster than the spleen, suggesting greater usefulness of pulmonary tissues for early PMI estimation, whereas splenic tissues serve as a more reliable indicator during later stages of decomposition.

Key Words: histotaphonomy, postmortem interval, spleen, lungs, decomposition