Objective: To investigate the distribution and topography of nervous structures within the renal pelvis and upper part of the ureter of pigs, and thus help to determine the origin, propagation and mechanisms of the modulation of pelvi-ureteric peristalsis.
Materials and methods: Whole-mount preparations of renal pelves from adult pigs were stained using a universal immunostaining method with streptavidin-alkaline phosphatase. Anti-neuron-specific enolase antibody and anti-neurofilament antibody were used as neuronal markers.
Results: The patterns of neuronal structures differed between the renal calyces, renal pelvis and upper ureter. In the calyx, there was one single dense nerve plexus; this network contained relatively thin nerve fibres running both circularly and longitudinally. In the wall of the renal pelvis and upper ureter there were two neuronal plexuses, one submucosal and another within the muscular layer; these nerve fibres were mainly orientated longitudinally. Some single nerve cells were also found at the pelvicalyceal border.
Conclusions: These findings suggest a potent nervous system within the upper urinary tract of pigs that connects the renal calyces with the renal pelvis, pelvi-ureteric junction and ureter. The presence of these dense neuronal networks and nerve cells within the wall of the renal pelvis and ureter suggests that propagation, coordination and modulation of pelvi-ureteric peristalsis in pigs may arise through intrinsic nervous stimulation.