Intramural ganglia in the human urethra

The urethras from five patients with a thoracic or cervical spinal cord lesion and one patient with carcinoma of the bladder were studied immunohistochemically for neuropeptide Y and vasoactive intestinal polypeptide. Autonomic ganglia, containing two to 21 nerve cell bodies, were found in the smooth and striated muscle regions of the intrinsic external urethral sphincter; they were present rarely in the distal urethra and were absent from the prostatic urethra. Neuropeptide Y immunoreactivity was observed in some of the nerve cell bodies (diameter 25 to 50 microns). Vasoactive intestinal polypeptide immunoreactivity was observed in small cells (diameter 15 to 25 microns.) in the urethral smooth muscle and in the walls of blood vessels that resembled small intensely fluorescent cells but may be nerve cell bodies. Both neuropeptide Y- and vasoactive intestinal polypeptide-immunoreactive nerve fibres were found in the smooth muscle and around blood vessels in the urethra of all patients. Both types of peptide-containing nerves were found associated with striated muscle of the intrinsic external urethral sphincter in patients with spinal cord injury, but only vasoactive intestinal polypeptide-immunoreactive nerves were found in the patient with carcinoma of the bladder in this region. The functions of the autonomic ganglia and vasoactive intestinal polypeptide- and neuropeptide Y-immunoreactive nerves in the human urethra remain to be elucidated.