After the MWM test, three mice were selected randomly from each group and anesthetized with 7% chloral hydrate. Then these mice were perfused with phosphate-buffered saline (0.1 M, 4 °C) via the ascending aorta, followed by 4% paraformaldehyde until the tail and limbs were rigid. Thereafter, the brains were removed and cut in half. Half of the brain was fixed with 4% paraformaldehyde for seven days and cut into coronal sections (4-µm thick) for hematoxylin-eosin (H&E), Nissl and TUNEL staining (Yang et al., 2014; Liu et al., 2015). The other half was fixed with 2.5% glutaraldehyde for electron microscope detection.