Fig. 3

PSNs with high TRKC levels preferentially survive the cell death period. a Temporal fate mapping of TRKC^High PSNs by 4-OHT (low dose, 0.02 g/kg). b–d Injection of TrkC^CreER;R26^tdTOM mice with low dose of 4-OHT at E11.0; DRG analyzed at E11.5 with recombination in few (b), preferentially high TRKC PSNs (c, d) (P < 0.001). Frequency distribution of TOM⁺ PSNs according to TRKC intensity (c) and pie charts (d) illustrating the large proportion of TOM⁺ cells among TRKC^High PSNs. Scale bar: 50 μm. e, f Percentage of recombined PSNs at E11.5 and E13.5 in DRGs from TrkC^CreER;R26^tdTOM animals after 4-OHT injection at E11.0 (*P < 0.05, Student’s t-test; n = 2 litters with 6 embryos, E11.5; 2 litters with 5 embryos, E13.5). g The percentage of labeled PSNs does not change between E11.5 and E13.5 in R26^CreERT2;R26^tdTOM embryos injected at E11.0 with 0.032 g/kg 4-OHT (n = 4). Similarly, the recombination rate in TOM⁺ PSNs does not change between E14.5 and E16.5 in TrkC^CreER;R26^tdTOM embryos after injection at E14.0 with 0.02 g/kg 4-OHT (n = 2). Unpaired Student’s t-test. h Whole-mount immunostaining for TRKC, NF160 and RFP of E13.5 forelimb from TrkC^CreER;R26^tdTOM embryos injected with low dose 4-OHT at E11.0. Insert shows restricted number of TOM⁺ fibers dispersed amongst TRKC⁺ axons. Scale bar: 200 μm. i Pattern and color-coded depth (in micrometers) of innervation of TRKC⁺, NF160⁺ and RFP⁺ nerve fibers (processed from h) of E13.5 forelimb from TrkC^CreER;R26^tdTOM embryos injected with a low dose of 4-OHT (0.02 g/kg) at E11. The pattern and depth color code reveal similar territories (in all dimensions, xyz) of innervation of the TOM⁺ PSNs compared to all axons (NF160). Scale bar: 200 μm. j Scheme illustrating the preferential selection of TRKC^High PSNs during the cell death period. Source data are available as a Source Data file