In vitro, ex vivo, and in vivo secretagogin silencing (siRNA) does not affect cell survival or the expression of synaptic markers. (A–A′′) Control experiments for secretagogin siRNA selectivity. The density of live cells as determined by counting Hoechst+ nuclei was identical after the application of scrambled or secretagogin-specific siRNA in P5 dissociated RMS cultures. (B and B′) Secretagogin silencing in SH-SY5Y neuroblastoma cells left the expression of the pre- and postsynaptic markers synaptophysin and PSD-95, respectively, unaltered. (C and C′) Synaptophysin expression did change after secretagogin silencing in P5 RMS explants. (D–D3) In vivo gene silencing did not affect the density of Hoechst+ cells at the application site immediately dorsal to the RMS (areas within the dashed boxes). High-power images are shown in D2 and D2′. inj, injection site; qu, quantification. (Scale bars: 20 μm in A, D, and D1; 8 μm in D2.)