Fig 1.

Subcutaneous tumorigenesis in immunodeficient nude mice injected with long-term cultured hsNSCs (A, B). Tumors were observed in 2 out of 15 mice. Karyotype analyses were performed on passage 17 hsNSCs and T1 cells. The karyotype of hsNSCs was analyzed using the G-banding staining method. Normal human diploid karyotype was maintained throughout the in vitro culture period (C), whereas a large number of different numerical and structural chromosomal aberrations were detected in the T1 cells (D). H&E staining (E, F) showed that the neoplasias proliferated actively. Large areas of necrosis surrounded by highly packed tumor cells were observed within the tumors. Many mitotic figures were demonstrated. Immunohistochemistry results indicated that the isolated tumors were immunoreactive for neuroendocrine tumor markers CgA (G) and NSE (H), but were negative for CD99 (I), cytokeratin AE1/AE3 (J), synaptophysin (K) and GFAP (L). Black arrowheads show the mitosis of spindles or equatorial planes. Scale bar: E, 100 µm; F-L, 20 µm.