20 mg/mL fibrin gels containing 10 ng/mL FGF-2 (A–C), VEGF165 (D–F), BMP-2 (G–I), and PDGF-BB (J–L) were placed on CAM of 10 day old chick embryos. Three days post-placement on the CAM, embryos were intravitally injected with QDs and histologically processed as in Figure 1. Brightfield (A, D, G, J) and fluorescence (B, E, H, K) images were obtained using the M2BIO stereoscope. Fluorescence overlays (C, F, I, L) are shown for comparison of blood vessel and fibrin localization. In panels A, D, G, and J “f” and “c” indicate the location of the fibrin and CAM, respectively. Scale bars in all images are 200 μm.