(a,b) Neuronal cell counts of SCGs from Rab7+/+; Th2a-CreER, Rab7f/+; Th2a-CreER and Rab7f/f; Th2a-CreERmice at P7. Tamoxifen was administered at E14 (0.5 mg) to induce Cre expression (n = 3). Scale bar: 100 μm. (c,d) Rab7+/+; Th2a-CreER and Rab7f/f; Th2a-CreERmice were treated with 1 mg tamoxifen at P7 and SCGs were harvested at P14. TrkA signaling was assessed by P-Trk Y490 and Y785 staining. Synaptic organization was assessed by VAChT (green) and Homer (magenta) staining, and VAChT/Homer colocalization (n = 3). (e–g) Sympathetic neurons harvested from P0 Rab7f/f pups were grown in microfluidic chambers and infected with a lentivirus expressing the Cre recombinase. Cells were incubated with NGF in the distal axon compartment and anti-NGF and the caspase inhibitor, BAF, in the cell body compartment for 48 hr, and TrkA signaling was assessed in axons and cell soma was assessed by P-Trk Y785 immunostaining (e,f). Alternatively, retrograde NGF-dependent neuronal survival was assessed (g) (n = 3). (h,i) The Flag-TrkA transport assay was performed in sympathetic neurons infected with lentivirus expressing either a control shRNA or an shRNA against Rab7. The accumulation of Flag-TrkA punctae in cell bodies, which represent retrogradely transported TrkA, was assessed (n = 3). Scale bar: 10 μm (c,e,h). Data are presented in dot plots (b,d,i) or box plots (f,g). *p<0.05, **p<0.01 and ***p<0.001 by one-way ANOVA with a Tukey’s post-hoc test (b,g) or a two tailed unpaired Student’s t test (d,f,i). See also Figure 3—figure supplement 1.