Study on Postmortem Changes of Multiple Organs in Rats under Different Temperatures
Date Issued
2015
Date
2015
Author(s)
Hsu, Chih-Chin
Abstract
Animal welfare and medical disputes are getting public attention to raise development of veterinary forensic medicine. Estimation of postmortem interval (PMI) is always correlated with observation in postmortem changes (PMCs). However, PMCs are deeply influenced by extrinsic and intrinsic factors, leading to misestimate PMI frequently. Up to date, studies explored PMCs are almost at macroscopic level, but less investigation by light microscopy. The study aims to correlate PMCs in gross examination and light microscopy, following with immunohistochemistry to estimate PMI. The rats were sacrificed by humane method, whole bodies were stored under 25℃ and 35℃ individually, and then sampled from day 0 to 7. The major organs, including the brain, heart, liver, spleen, lung, kidney, skin, and m. longissimus dorsi were observed grossly, then fixed in 10% neutral formalin for microscopy and immunohistochemistry. As for the antibodies of immunohistochemistry, including CD3, CD79a, Desmin, Factor VIII, GFAP, Myoglobin, NF, SMA, and Vimentin were used. The results showed that postmortem rate in 35℃ was faster than 25℃, and the changes presented regularly. In gross, such as discoloration, abdominal swelling, and texture of the organs; however, the body temperature, rigor mortis, decomposition fluid, and the texture of m. longissimus dorsi were nonspecific; alopecia was faster in 25℃. In light microscopical examination, only spleen change was nonspecific, others were faster in 35℃. Some changes found in this study are worth our attention, such as in 1 dpm (day of postmortem), the spongy like change noted in the white matter might be comfused with spongiform change in the central nervous system; the intracytoplasmic vacuoles of hepatocytes should differentiate with lipid droplets of fatty liver; initiation of small amount of edematous exudates within the alveoli might be misdiagnosed in lung edema. In immunohistochemistry, most of the antibodies revealed positive to negative, and signals disappeared in 2-3 dpm; however, in CK, desmin, GFAP, myoglobin, and SMA showed variable results under different organs, dpm, and temperatures, some of them even displayed cross reaction, this leads difficulties in interpretation. The results from gross, microscopy, and immunohistochemistry study are summarized in flow charts for the purpose of PMI estimation, and it further needs to put it into practice of forensic cases to confirm the feasibility.
Subjects
Postmortem changes
postmortem interval
rats
gross
light microscopic
immunohistochemistry
temperatures
SDGs
Type
thesis
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