Fig. 1.

Type III Nrg1 is required for sensory neuron survival. (A) Type III Nrg1 is expressed in subsets of dorsal root ganglion (DRG) neurons. E17.5 DRG sections were co-labeled for type III Nrg1 and CGRP (a,e,i), TrkA (b,f,j), TrkB (c,g,k) or NF200 (d,h,l). Arrows indicate double-labeled neurons. See also supplementary material Fig. S1. (B) DRG sections from wild-type (WT) or type III Nrg1^–/– mouse embryos were labeled for Islet1/2 (a,b) or cleaved caspase 3 (cl-Casp3; c,d). (C) Quantification of Islet1/2⁺ neurons in WT and mutant DRG at E14.5, E16.5 and E18.5. (D) Quantification of cl-Casp3⁺ neurons in WT and type III Nrg1^–/– (KO) DRG sections at E14.5 and E18.5. DRG were co-labeled for PGP9.5 (Uchl1) to identify sensory neurons, and numbers represent the fraction of double-labeled neurons. Mean ± s.e.m. ^*, P<0.01; ^**, P<0.001 (ANOVA with post-hoc Fisher’s PLSD test). Scale bars: 25 μm in A; 100 μm in B.