Localization of HCs in PC3 tumor tissues. (A-E) Sections of PC3 tumor tissues from PC3 tumors with a volume of (A) more than 500 mm³, (B-C) 60 to 70 mm³, and (D-E) 100 to 120 mm³ were double stained with anti–PECAM-1 mAb (dark blue) and anti-CD45 mAb (red) (A,B,D) or with anti–PECAM-1 mAb (dark blue) and anti–c-Kit mAb (red) (C,E). Arrows in panel C indicate a small capillary at the tumor edge. Panels C,E are serial sections of panels B,D, respectively. (F) Colon26 tumor tissue section from a tumor with a volume of 60 to 70 mm³ was stained with anti–PECAM-1 mAb (dark blue) and anti–c-Kit mAb (red). Arrows indicate cells that are positive for c-Kit. The dotted line (B-F) shows the border between the fibrous cap surrounding the tumor mass and the tumor mass. Insets (D-F) show high-power views of the area indicated by box. The bar in panel A indicates 50 μm (A-C). The bar in panel D indicates 100 μm (D-F).