Dystroglycan but not Bcam is required for postsynaptic maturation. (A) AChR clusters in Dag1^loxP/loxP;Pax3-Cre mice were plaque-like in topology. (B) NMJs in Bcam^−/− mice are indistinguishable in topology from those in littermate controls. Longitudinal sections of adult tibialis muscles were stained with antibodies to neurofilaments and SV2 (nerve, green), and Alexa 594–BTX (AChR, red). Bars, 10 μm.