Intra-arterial adenoviral mediated transfection of tumors grown in the cremaster muscle of athymic nude rats. Tumors from two different animals are shown. The cremaster muscle of athymic male nude rats were inoculated with 5 × 104 cells of the human bladder carcinoma cell line T24. Ten days after tumor cell implantation, the cremaster muscle flap was intra-arterially infused with 1 × 109 pfus of a recombinant adenovirus encoding the green fluorescent protein gene (Ad5-CMV-GFP) and were left to incubate for 1 hour. Seventy two hours after viral infusion cremasters were set up for standard micro-photography and fluorescent confocal microscopy and photography as described in materials and methods. Texas red fluorescent micro beads were used to counter stain the muscle and tumor vasculature. Panel A: 2X Photographic image of a tumor using a standard stereoscopic microscope. Panel B Confocal fluorescent photography of the same tumor. Panel C: 2X Photographic image of a tumor using a standard stereoscopic microscope on a second animal. Panel D: Confocal fluorescent photography of the same tumor. Green fluorescent protein can be seen expressed throughout the tumor mass. A concentric neoangiogenic response can be seen as well.