Figure 4.

Target-derived BMP4 promotes sensory neurite outgrowth. A. Dissociated dorsal root ganglion neurons grown on collagen coated plates showed increased neurite outgrowth in the presence of 10ng/ml or 50ng/ml BMP4 (*P≤0.007). B. Vaginal smooth muscle cells immunostained for α-smooth muscle actin (red) were grown on collagen-coated plastic. Dorsal root ganglion neurons immunostained for peripherin (green) were plated on smooth muscle cells, and most extended neurites that made contacts with muscle cells at 48h. C. Vehicle treated co-cultures immunostained for peripherin showed many neurites. D. Co-cultures treated with noggin (250ng/ml) had fewer neurites. E. Quantitative analysis confirmed a reduction in neurite outgrowth per neuron in noggin treated co-cultures (**P=0.001). F. Neurites elaborated by neurons grown directly on smooth muscle co-cultures (Control) are reduced by the addition of a BMP4 function-neutralizing antibody (#P=0.005 G, H). Anti-BMP4 was equally effective in reducing axon outgrowth when smooth muscle cells were grown in transwell inserts (H, Control-T, Anti-BMP4-T, ##P=0.004). Bars in C and F = 50 µm.