Abstract: Histologically intact tissue of human gast ric carcinoma SGC - 7901 maintained by passage in the subcuitis of nude mouse was implanted orthotopically into the stomach wall of SCID mouse. Their biological properties ,ways of invasion and metastasis and morphological characteristic were studied , All mice with t ransplanted tumours exhibited 100 % t ransplantability and metastatic ability ,as well as various manifestation reminescent of tumour behaviour in patients. These included :local growth ,regional invasion ,spontaneous metastasis to lymph nodes and liver ,and peritoneal seeding. RT2PCR confirmed that t ransplanted tumours had identical characteristic of expression of cell adhesion molecules P2selectin as f resh human specimens of gast ric cancer. This indicated that the microenvironment in the t ransplantation site had certain influience on the biological behaviour of the t ransplahted tumours which grew independentely in the stomach of SCID ,making a better model than that of subcutaneously t ransplanted tumours for futther study on invasion and metastasis mediated by adhesion molecules and experimental therapy further of human gast ric cancer.

Key words: Orthotopic implantation, Gast ric canner, P2selectin, RT-PCR