In Vivo Nerve-Specific Targeting using Oxazine 4 in Rats. A) 1 µmol of Oxazine 4 was injected intravenously into SD rats 4 h prior to imaging. Shown are color image, NIR fluorescence, a merged image of the two (pseudo-colored in lime green), and magnified images of NIR fluorescence acquired using the FLARE imaging system. Arrowheads indicate small branches of main nerves, which cannot be seen in color image. Scale bars = 1 cm. B) H&E, phase image, NIR fluorescence (Oxazine 4, 700 nm NIR), and immunostaining (right) of small branched peripheral nerves obtained from A using an anti-myelin antibody conjugated with IRDye 800CW. Squares on low-resolution images indicate the positions of magnified images. Pseudo-colored red and green colors were used for 700 nm and 800 nm channel images, respectively. Scale bars = 100 μm. Images are representative of N = 5 independent experiments. All NIR fluorescence images have identical exposure and normalizations.