Figure 5.
PNCs rarely form tumors following transplantation. (A) Design of orthotopic transplantation assay. We isolated 5 × 105 PNCs or tumor cells from ptc+/− or M-ptc mice and transplanted them into the cerebellum of SCID-beige hosts to assay for tumorigenicity. (B) Incidence of tumors from transplanted PNCs or tumor cells. (C–E) PNCs and tumor cells were transplanted as described above and hosts were sacrificed 2 wk later. Cerebellar sections were stained with antibodies specific for βgal to detect transplanted cells (C,D), Ki67 (C,E), or NeuN (E). (C) Two weeks after transplantation, βgal+ tumor cells had formed a proliferating (Ki67+) mass in the cerebellum. (D) βGal+ PNCs could also be detected at this stage. (E) Although some of these cells were proliferating (Ki67), many had exited the cell cycle and expressed the differentiation marker NeuN. Magnification 20×.