Skin-derived NT3 does not regulate DRG neuron Trk expression. A–D, Immunostaining for NF200, TrkB, and TrkC in T7 DRG sections from P0 control littermate and K14; Ntf3CKO mice. Asterisks indicate double-labeled cells. E, Numbers of Islet1/2+, NF200+, TrkB+, TrkC+, and TrkB+TrkC+ neurons in P0 T7 DRGs (n = 6 mice/genotype). Error bars represent the SEM, and asterisks indicate statistically significant differences between genotypes. ***p < 0.001. Scale bar, 100 μm.