Expression of SALL4 and CD133 in IH tissues. (A) Immunohistochemistry staining of proliferative (1,3) and involuting (2,4) IH tissue sections with anti-SALL4 and CD133 antibodies. Magnification: 100x, inset 200x. (B) 1, Phase contrast image of IHs tumor spheres forming on Petri dishes with surrounding mature endothelial cells and/or fibroblasts. This was observed after 3 days of culture in serum-free media. Magnification: 100 ×. 2, the tumor spheres continue to grow under serum-free conditions while mature cells such as endothelial cells and fibroblasts do not. Magnification: 100x. 3, phase contrast image of high density tumor spheres in culture. Magnification: 100 ×. 4, comparison of IH tumor sphere (left) and induced pluripotent stem cell clone (right). Magnification: 100 ×.