Brain of tumor-bearing mice observed by eyes and under lower power lens. A-C: brain metastasis tissues was implanted in right caudate nucleus. Tumor had grown to the brain surface of right hemisphere. The boundary between tumor and normal tissues was very clear seen by eyes (A and B) or under microscope(C arrow). D-F: the transplantation position of glioma was right caudate nucleus too. There was no tumor can be seen on the surface but brain edema was apparent. Under microscope Tumor cells were seen extensively invading to adjacent brain tissues.