Myelinated Aδ-fiber visceral afferents of the urinary bladder transduce and convey mechanosensory signals to the spinal cord via the pelvic nerve and are essential for micturition. We have recently identified a new approach to selectively label this afferent class in rats using a novel adeno-associated virus with tropism for peripheral neurons, AAV-PHP.S (PMID: 38102980). Our aims were to define the structural properties of myelinated bladder afferents within the pelvic nerve and bladder wall; and to characterize the structure of myelinated afferents in the urethra, where sensory function is less well understood. Studies were performed in organ whole mounts from male and female Sprague-Dawley rats. All interventions were performed under anaesthesia. Myelinated afferents innervating the bladder were identified in the pelvic nerve by combining AAV-PHP.S (intravenous), microinjection of cholera toxin subunit B into the bladder and neurofascin immunofluorescence (node visualisation). This revealed heterogeneity in axon diameter (0.5-1.5 µm) and internode length (115-891 μm). Terminal structures of myelinated afferents varied in shape between bladder dome, bladder neck and urethra. In the urethra the terminal fields varied across region and sex. The intramural component of myelinated afferents was devoid of myelin in the bladder but not the urethra. This study provides the first detailed structural characterization of myelinated bladder and urethra afferents, revealing several major differences between organs and regions. Our data will inform physiology and modeling of sacral visceral afferent function and optimization of neuromodulation protocols targeted to lower urinary tract conditions.