Angiogenic properties of ARPC and ARPC-derived spheroids. Microscopic (A-C) and macroscopic (D-F) images of CAMs transplanted with a silicon ring alone (A, D) or with a silicon ring containing inside RPTECs (B, E) and ARPCs (C, F). The A-C sections are H&E stained; the arrowheads indicate some vessels and the arrow in C a group of ARPCs cells near the vessel. In G, histograms showing the postimage analysis of vessel total area, vessel total length, and number of vessel branching points, expressed as percent variation in RPTECs and ARPCs compared with the control (silicon ring alone). (H) Histograms showing the postimage analysis of vessel total area, vessel total length, and number of vessel branching points, expressed as percent variation in ARPCs and ARPC-derived spheroids compared with controls. (I-K) Microscopy images of CAMs transplanted with a silicon ring alone (control, I) or a silicon ring containing inside ARPCs (J) or ARPC-derived spheroids (K). The arrowheads indicate some CAM vessels and the arrows in J and K indicate a group of ARPCs and ARPC-derived spheroids, respectively, near the vessels. (L-N) Fluorescence microscopy images of a CAM vessel (arrowhead) in a control (L), in PKH26-labeled ARPC-transplanted CAM vessels (arrowhead, M) and in CAM vessels (arrowhead) transplanted with spheroids generated from PKH26-labeled ARPCs. The arrows in (M) indicate the ARPCs around the vessels. The arrows in (N) indicate the spheroids near the vessel. Scale bar: A-K 100 μm; L-N 25 μm.