Immunoreactivity for descending projections to lumbosacral areas involved in micturition. A–C, Bright-field photomicrographs showing serotonin immunoreactivity in the DL. High levels of the immunoreactivity are seen in uninjured (A) and 12.5 mm SCI (B) animals, and virtually no labeling is seen in the 50 mm SCI animal (C). D–F, Bright-field photomicrographs showing CRF immunoreactivity in the SPN. Progressively decreased levels of immunoreactivity are seen in uninjured (D), 12.5 mm SCI (E), and 50 mm SCI (F) animals. Scale bar, 20 μm.