Fig 4. Human breast cancer cells are more metastatic in NSG mice than in nude mice in an experimental metastasis model.

MDA-MB-231 cells were injected into the heart of both nude (n = 7) and NSG (n = 8) mice and metastases were analyzed. A. Fluorescence images (white area is fluorescent tumors) were taken using a Zeiss SteroDiscovery.V12 fluorescence dissecting microscope with an AxioCam MRm digital camera. Representative images are shown from several different organs. Arrows, examples of numerous micrometastases in the lungs and brain of NSG mice (≤10 mm²). Bar, 2 mm. B. The metastases in the lungs, liver, brain (cranial and caudal) and bones (spine, ribs, scapula, radius, humerus, pelvis, femur and tibia) were enumerated for each mouse using Image J.