AlexaFluor546-tagged siRNA uptake in lumbar DRG (A, C, E) and spinal cord (B, D, F). Vehicle (10 μL) (C, D), siRNA with vehicle (2 μg/ 10 μL) (A, B), or siRNA without vehicle (2 μg/ 10 μL of aqueous annealing buffer) (E, F) was given intrathecally as a single injection. Tissues were harvested and processed 24 hr later. Images of the DRG were taken using a 20× objective lens and that of the spinal cord taken using a 40× objective lens. In all the fluorescence labeled cells, the labeling was punctate and peri-nuclear, and labeling intensities varied among cells. In the spinal cord (B), labeled cells were distributed widely in both the dorsal horn and the ventral horn. The images in B, D, F were taken from laminae I/II of the dorsal horn. Scale bar for the DRG images shown in panel E is 50 μm; scale bar for the spinal cord images shown in panel F is 25 μm.