Density of NRG1-containing synapses at phrenic motoneurons.
A. The number of NRG1 synapses at PhrMn soma correlates with soma surface area (r2 = 0.45, p<0.01). Spearman's ρ is 0.62 (p<0.0001).
B. The number of NRG1 synapses at the primary dendrites of PhrMn also correlates with primary dendrite surface area (r2 = 0.38, p<0.01). Spearman's ρ is 0.66 (p<0.0001).