电流斑的光镜和扫描电镜观察以及能谱测定

为了找出电流斑在扫描电镜下的特征性改变,作者用扫描电镜和能谱测定,配合光镜观察,对电击死者的22个皮肤电流斑和尸体上造成的18个皮肤电流斑和金属灼伤,进行了对比观察。结果表明,光镜下电流斑的形态改变与过去学者所述基本一致。非典型的电流斑难与热灼伤相鉴别。扫描电镜下电流斑的形态特征为:(1)损伤底部和壁上可见散在的小孔穴,直径为30～100μm,深浅不一,边缘不规则;(2)损伤组织表面大量细胞碎屑和颗粒;(3)组织和脱落细胞表面有裂纹;(4)损伤区内有散在的异物颗粒沉积,其形态为球形、方形或不规则形,电子密度较大。作者认为这些改变是电流作用造成,热灼伤不具备这些改变,故在扫描电镜下极易区别电流斑和热灼伤。所有电流斑均可测出与导体化学组成相同的金属元素。作者提出,扫描电镜下的上述形态改变和能谱测定结果可以作为诊断电流斑的依据。

MORPHOLOGIC OBSERVATION OF CURRENT MARKS UNDER LIGHT MICROSCOPE (LM)AND SCANNING ELECTRON MICROSCOPE (SEM)WITH ENERGY DISPERSIVE X-RAY(EDX)

In order to find out the characteristic changes of current marks under the SEM, 22 samples of the cur-rent mark from eight corpses died of electrocution and 18 experimental current marks made on dead bodywere studied under the light microscope and scanning electron microscope. The changes were compared withthose of 15 heat-burn injuries of dead body. The results indicated that the histopathologic changes of current marks under the light microscope weregenerally in accord with those of previous studies. The problem to be settled is that it is still difficult to dif-ferentiate atypical current marks from heat-burn injuries. The morphologic changes of current mark underthe SEM were as follows: (1) Small holes with different size, 30 ～100 micron in diameter, and depth werescattered on the surface of the bottom as well as along with the wall of the wound canal; (2) Abundant ofcellular debris and particles adhered to the surface of the lesions; (3) On the surface of the injured tissuesand the detached cells some branching cracks and fine crackles were seen. (The changes were more obviousin antemortem electrocuted lesions); (4) Many dispersive metal particles with high electron-density deposit-ed in the lesions and took the form of spherical, square or irregular shapes. The authors emphasized thatthese morphologic changes were the characteristics of current marks. According to these changes, it is easyto distinguish current marks from that of the heat-burn injuries under the SEM. In current marks, the metalparticles which contained the same elements as conductor were identified under the SEM with EDX, whileno metal particles could be found in heat-burn injuries. The authors suggested that the morphologic changesobserved under the SEM and studied by EDX could be the diagnostic evidence of current marks.