Dendritic transport of rat BC1 RNA: impairment after coinjection with SLE anti-BC IgGs. After preincubation with IgGs, radiolabeled BC1 RNA was coinjected into sympathetic neurons in primary culture. Coinjection was performed with IgG HS4 (A, B), IgG SLE S1 (C, D), or IgG MS1 (E, F). In dark-field photomicrographs (A, C, E), labeling signal appears as white silver grains. Typical neuronal morphology and dendritic extent of sympathetic neurons in culture (Muslimov et al., 2011, 2014) are observed in phase-contrast photomicrographs B (corresponding to dark-field photomicrograph A), D (corresponding to dark-field photomicrograph C), and F (corresponding to dark field photomicrograph E). Scale bar, 50 μm. Numbers of cells analyzed: A, B, 7 neurons, 28 dendrites; C, D, 8 neurons, 28 dendrites; and E, F, 7 neurons, 28 dendrites. Quantitative analysis (G) indicates that IgG SLE S1, but not IgG HS4 or IgG MS1, significantly reduces dendritic delivery of BC1 RNA.