Fig. 3. TEM results of the ultrastructural changes in hippocampal neurons. The ultrastructure of hippocampal neurons was observed by TEM and the photos were taken. Shown are the representative images. The control group (a) and 5 mg kg^–1 group (b) have a normal ultrastructure of hippocampal neurons including mitochondria (pointed by blue arrows). Mitochondrial swelling can be found in hippocampal neurons in the 10 mg kg^–1 group (c) (pointed by blue arrow). In the 20 mg kg^–1 group (d), mitochondrial swelling was more obvious and existed with a small amount of cavitation mitochondria (indicated by blue arrow).