Serial observations on an orthotopic gastric cancer model constructed using improved implantation technique

Figure 1 Macroscopic examination of the primary tumor in SGC-7901 model. The gastric cavity occupied by primary tumor was found vanished, and pylorus was obstructed totally (arrows).

Figure 2 Histopathologic structure of SGC-7901 tumors by HE staining. A: Tumor cells showed nuclear polymorphism, nuclear hyperchromatism, and much mucus in the cytoplasm (× 200); B: The primary tumor destroyed muscularis mucosae (arrows) (× 100); C: The lymph nodes were infiltrated by metastatic tumor (arrows) (× 100); D: Metastases (arrows) infiltrated into the liver (× 200); E: Metastatic tumor (arrows) invaded the kidney (× 100); F: Tumor (arrows) metastasized to the lung and surrounded bronchia or bronchiole (× 40); G: Cast-off tumor cells were detected in ascites (× 200).

Figure 3 Immunohistochemistry of SGC-7901 tumor by streptavidin-peroxidase method. Expression of Cytokeratin 20 (CK20) protein was positive, which was stained brown in the cytoplasm in the tumor of stomach (A × 40) and liver (B × 100).

Figure 4 Immunostaining of SGC-7901 tumor using streptavidin-peroxidase method. Epithelial membrane antigen signal stained brown in the cytoplasm was positive in the tumor of stomach (A × 40), lymph node (B × 40) and lung (C × 100).

Figure 5 The curve of tumor growth at different time points. The tumor volume gradually increased from the 6th wk after implantation, and reached a peak at the 12th wk.