Figure 3

The distribution of dural afferent neurons expressing the neuropeptide CGRP. (A) Representative images of TG sections containing FG⁺ or DiI⁺ dural afferent neurons and neurons exhibiting CGRP-ir. Arrowheads indicate double-labeled FG⁺/CGRP⁺ and DiI⁺/CGRP⁺ dural afferent neurons. (B) The abundances of CGRP⁺ neurons in the V₁/V₂ divisions of the TG, in the FG⁺ skin afferent neurons, and in the FG⁺ or DiI⁺ dural afferent neurons (n = 3 mice in each group; *** p < 0.001, two-tailed t-test). On average, 685 V₁/V₂ neurons from each mouse were counted in each group. On average, 296 FG⁺ skin afferent neurons, 233 FG⁺ dural afferents, and 285 DiI⁺ dural afferent neurons were counted from each mouse. (C) The size distribution of the CGRP⁺ dural afferent neurons (filled bars, n = 99 neurons pooled from three mice) is similar to that of the CGRP⁺ neurons in the V₁/V₂ divisions of the TG (open bars, n = 661 neurons pooled from three mice, p = 0.7, Mann–Whitney U test). (D) The size distribution of the CGRP⁺ neurons (open bars, the same neurons as in C) and total neurons in the V₁/V₂ divisions of the TG (grey bars, n = 2041 neurons pooled from three mice). (E) The size distribution of the CGRP⁺ dural afferent neurons (filled bars, the same neurons as in C) and total FG⁺ dural afferents (grey bars, n = 700 neurons pooled from three mice).