2.4 Histopathological analysis
Lung and liver tissues were rapidly dissected from C57BL/6 mice, fixed in 4% paraformaldehyde for 24 h, and embedded in paraffin. Tissue wax blocks were sectioned and stained with H&E (Sangon-Biotech, China). The fixed specimens were stained with H&E after cutting into 4-mm transverse sections using a semi-automatic rotating Thixotrope (Leica Microsystems Trading (Shanghai) Co., Ltd). Pathological changes were recorded under a light microscope (Nikon, Japan).