Fig. 4.

Competitive control of synapse density by ephrin-B3. (A) Hetergenotypic cultures of P0 wt and eB3^−/− littermate mice. Unlabeled neurons of one genotype were plated followed by a second group labeled by electroporation with GFP. Cultures were stained at DIV 10 with anti-GFP (green), anti-PSD-95 (red), and anti-VGlut1 (blue) antibodies. Arrows indicate synaptic puncta identified by colocalized PSD-95 and VGlut1 immunostaining. (B) Quantification of synaptic puncta density for GFP-labeled neurons in heterogenotypic cultures (wt/wt, n = 44, eB3^−/−/wt, n = 67, eB3^−/−/eB3^−/−, n = 50, and wt/eB3^−/−, n = 70). (C) Model of experimental design and results. (Scale bar, 3 μm.) Error bars indicate SEM. * P < 0.002, ** P < 0.0003.