蠅蛆影響豬肌肉組織死後變化的觀察

Abstract

近年來在國內外動物福利及動物權日漸受到重視，促使許多隱藏的醫療糾紛及動物受虐案件浮上枱面。因此動物法醫變得越來越重要，藉由各種死後變化的觀察，可以協助釐清造成死亡原因、機制、死亡方式及經過時間，用以提供法律上的證據；然而在動物法醫學的發展中，許多死後變化的基礎數值尚未建立。其中屍體的腐敗速度受許多內在及外在因素的影響，環境中嗜屍動物是影響屍體腐敗速度的外在因素之一；過往法醫昆蟲學家對於嗜屍昆蟲已有詳盡且多方面的研究，而對於受嗜屍昆蟲影響的屍體變化的研究卻很少，本研究試著觀察蠅蛆對豬肌肉組織死後變化的影響，希望能藉由組織形態學、免疫化學染色及生物統計等方法，尋找死後變化的規律，進而更精確的推估動物死亡時間。實驗結果顯示肌肉組織在蠅蛆作用下，對組織有物理性及化學性的影響，而有無蠅蛆參與作用的肌肉組織形態學出現明顯差異；利用免疫組織化學染色，偵測dystrophin、desmin及myoglobin等結構蛋白降解的比例，有無蠅蛆參與作用的實驗組與對照組，在第1天及第2天出現明顯差異，到第3天則無顯著差異。未來若能補上每小時的觀察、量化，統計上加以分析對照組與實驗組的陽性率差異，可能可以更準確的推測2天之內的動物死亡時間。

The interest in animal forensic medicine has increased greatly in the last few years due in part of an increasing awareness of the impact of animal welfare. The estimation of postmortem interval is one of the primary works in solving crime cases. However, limited methods were applied in forensic fieldwork until now. Given that the postmortem changes are dramatically influenced by numerous intrinsic and extrinsic factors, the better way to approach practical methods for estimating postmortem interval is to search factors which are involved in postmortem changes. The present study aims to investigate the postmortem changes of pig skeletal muscles under the influence of maggots. Histology and immunohistochemistry based methods were applied to observe and to quantify the morphological changes and proteolysis of skeletal muscle cells with or without maggot (Chrysomya megacephala) involvement. The results demonstrated that under maggot influence, physical destructions took place between maggots and debris of muscle tissues and the adjacent remaining myocytes underwent chemical destructions. Besides, the immunohistochemistry against dystrophin, desmin, and myoglobin showed that positive signals faded out significantly with time faster in groups with maggot effect than the control groups in the first day and the second day. These results suggested that the acceleration of postmortem changes can be illustrated by means of immunohistochemistry under maggot effect. Proteolysis profiles may be served as a potential tool for estimating postmortem interval.