Clarification of the Innervation of the Bladder, External Urethral Sphincter and Clitoris: A Neuronal Tracing Study in Female Mongrel Hound Dogs

Abstract

Many studies examining the innervation of genitourinary structures focus on either afferent or efferent inputs, or on only one structure of the system. We aimed to clarify innervation of the bladder, external urethral sphincter (EUS) and clitoris. Retrograde dyes were injected into each end organ in female dogs. Spinal cord, mid-bladder, and spinal, caudal mesenteric, sympathetic trunk and pelvic plexus ganglia were examined for retrograde dye-labeled neurons. Neurons retrogradely labeled from the bladder were found primarily in L7-S2 spinal ganglia, spinal cord lateral zona intermedia at S1-S3 levels, caudal mesenteric ganglia, T11-L2 and L6-S2 sympathetic trunk ganglia, and pelvic plexus ganglia. The mid-bladder wall contained many intramural ganglia neurons labeled anterogradely from the pelvic nerve, and intramural ganglia retrogradely labeled from dye labeling sites surrounding ureteral orifices. Neurons retrogradely labeled from the clitoris were found only in L7 and S1 spinal ganglia, L7-S3 spinal cord lateral zona intermedia, and S1 sympathetic trunk ganglia, and caudal mesenteric ganglia. Neurons retrogradely labeled from the EUS were found in primarily at S1 and S2 spinal ganglia, spinal cord lamina IX at S1-S3, caudal mesenteric ganglia, and S1-S2 sympathetic trunk ganglia. Thus, direct inputs from the spinal cord to each end organ were identified, as well as multisynaptic circuits involving several ganglia, including intramural ganglia in the bladder wall. Knowledge of this complex circuitry of afferent and efferent inputs to genitourinary structures is necessary to understand and treat genitourinary dysfunction. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

Determining integrity of bladder innervation and smooth muscle function 1 year after lower spinal root transection in canines

“…Pelvic plexus‐induced bladder contractions significantly decreased by 1 year after decentralization that included the transection of all sacral roots, the dorsal roots of L7, and the hypogastric nerves, bilaterally, confirming a previous finding that the L7 dorsal root plays an important role in bladder sensation . Despite the significant decrease in the strength of bladder contraction, the preservation of smooth muscle function and at least some nerve activity may encourage successful surgical reinnervation after long‐term lower spinal root injury.…”

“…The extensive decentralization in this study, which included transection of all sacral roots plus the dorsal root of L7, as well as the hypogastric nerves, bilaterally, was selected based on a previous study that identified the L7 dorsal root as one of the major sources of sensory neuron cell bodies innervating the bladder . Because these animals are part of a larger reinnervation study, we needed to ensure that the bladder was decentralized as much as possible to better evaluate the success of reinnervation.…”

A study on preganglionic connections and possible viscerofugal projections from urinary bladder intramural ganglia to the caudal mesenteric ganglion in the pig

“…; Pidsudko, ; Barbe et al. ). Therefore, differentiated chemical coding of the SPN may suggest that different populations of these perikarya supply discrete groups of CaMG neurons that project to specific targets.…”

“…; Pidsudko, ; Barbe et al. ). The ganglia themselves are targeted by nerve fibres (NF) arising from different sources.…”

“…The caudal mesenteric ganglion (CaMG) is one of the prevertebral autonomic ganglia and is a source of postganglionic innervation to a number of abdominal and pelvic organs (e.g. Miolan & Niel, 1996;Pidsudko et al 2001;Ragionieri et al 2013;Pidsudko, 2014;Barbe et al 2018). The ganglia themselves are targeted by nerve fibres (NF) arising from different sources.…”