Nanozoomer 2.0 rs optical microscope

After 24 d, all tumors were isolated for histopathological examination. Following fixation of the tumor samples in 10% formalin in phosphate buffer solution (PBS), sections (4–5-μm thick) of the tumor tissues were stained by hematoxylin and eosin (H&E). Ki67 is a nuclear antigen associated with cell proliferation, and its function is closely related to mitosis. To study the expression of Ki67, immunohistochemical staining was performed on tumor sections. Endogenous peroxidase activity was blocked by 3% H₂O₂ for 10 min at room temperature. After rinsing three times with PBS, an anti-Ki67 rabbit polyclonal antibody (1:200; Biovisualab, Shanghai, China) diluted in 0.1% PBS was added to the sections and incubated for 2 h at 4°C. The slides were rinsed with 0.1% PBS three times before adding the biotin-labeled rat anti-rabbit antibody (1:200; Biovisualab, Shanghai, China) diluted in 0.1% PBS and incubating at room temperature for 20 min. After rinsing three times, chromogenic detection was performed using 3,3′-diaminobenzidine (DAB) (Thermo Fisher, Nanjing, China). Histological examinations were conducted and photographs were taken using a NanoZoomer 2.0-RS optical microscope (Hamamatsu Photonics, Hamamatsu, Japan).