Distribution of CGRP- and GFRα3-immunoreactivity (IR) in the suburothelial plexus of whole mounts processed with diaminobenzidine (DAB). A–F: CGRP- (A–C) and GFRα3-IR (D–F) axons in the suburothelial plexus became progressively less dense towards the bladder dome (A, D: base; B, E: middle; C, F: dome). G–I: CGRP-IR axons formed closed loops (arrowheads) originating in the middle of axons (G) or on axon terminals (H, I). J, K: GFRα3-IR axons also formed closed loops (arrowheads) at the end of terminating axons (J) or in the middle of axons (K). J–L: Numerous small GFRα3-IR cells (arrows) were observed close to axons in the suburothelial plexus. M–R: CGRP-IR (M–O) and GFRα3-IR (P–R) terminals (arrowheads) in the suburothelial plexus. Scale bar = 100 μm in (A) also applies to (B–F); 50 μm in (G) also applies to (H–L); 50 μm in (M) also applies to (N–R). CGRP, calcitonin gene-related peptide; GFRα3, glial cell line-derived neurotrophic factor family receptor α3.