Résumé
Objective To study the ultrastructural changes of gunshot wounds at the brain stem and the cause of the death. Method A case died of the head injury and two cases died of gunshot wounds of the brain stem were studied. Brain stem tissues were taken 25 min after death. Tissue blocks from the tegmentum of the midbrain and the pons as well as the gray matter of the medulla oblongata in the deep portion of the base of the fourth ventricle were taken and were examined with ultramicroscopy and scanning electron microscopy. Results (1) The gunshot wound injuries inside the brain including burn and injuries caused by punch and pressure; (2) Although the primary gunshot wounds were located at the midbrain, the pathological changes extended to the whole brain stem; (3)The injuries of the axons and the nerve cells were more severe and extensive than those of the glia fibers. (4)The changes of the burn included condensation and degeneration of the myelin sheath and axonal cytoplasm, especially the mitochondria as well as edema of the myelin sheath and the axonal cytoplasm. The punch and pressure injuries included the torsion, deformation, fusion, compression, breach, torn and displacement of the axons with loss of cytoplasm as well as the deviation of mitochondria, micro ?neuro - fibrils and micro - tubules in the axons. Conclusion The severe and extensive injuries of the axons of nerve fibers in the brain stem might play an important role in the cause of death of gunshot.