Whole-mount preparation technique for the demonstration of the intramural innervation of the guinea pig ureter

Abstract

Purpose Previous histological studies investigating the innervation of the urinary tract have mainly used conventional sections in which the three-dimensional structure of the intramural innervation is difficult to achieve. In contrast the whole-mount preparation technique seems to provide a method for the visualization of the mesh like neuronal networks within the urinary tract. The purpose of the study was to investigate the distribution and regional variation of the intramural innervation in whole-mount preparations of the guinea-pig upper urinary tract. Material and methods Whole-mount preparation technique was employed in the guinea-pig upper urinary tract. Enzyme immunohistochemistry was carried using primary antibodies versus Neurofilament (NF), Tyrosine Hydroxylase (TH), Choline Acetyltransferase (ChAT) and Substance P (SP). Conventional nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase and Acetylcholinesterase (AChE) histochemistry was performed. The staining was evaluated using normal brightfield, fluorescence and laser confocal microscopy. Results NF-, TH-, ChAT- and SP-immunoreactive (-IR) nerves formed two distinct neuronal plexuses in the inner longitudinal muscle layer and the outer circular muscle. Additional TH-IR and SP-IR subepithelial networks were evident. Perivascular TH-, ChAT- and SP-IR fibres were demonstrated within adventitial and muscular layers. AChE positive nerves were revealed in all layers. Moderate NADPH-diaphorase positive innervation was found in the muscular layers. Renal pelvis, upper and lower ureter showed an overall enriched intrinsic innervation compared to the middle portion of the ureter. AChE positive and NF- and TH-IR ganglia were found at the ureteropelvic border and the distal ureter. Conclusions The technique of whole-mount preparation enables detailed morphological investigations of the intramural innervation of the upper urinary tract.