Innervation of the urinary bladder in higher primates

Area of Science:

• Neuroscience
• Urology
• Comparative Anatomy

Background:

• Understanding the neural control of the urinary bladder and sphincters is crucial for diagnosing and treating lower urinary tract dysfunction.
• Previous research has indicated complex innervation patterns, but precise mapping within spinal roots remains an area of investigation.

Purpose of the Study:

• To determine the segmental spinal cord origin of urinary bladder and sphincter innervation in Rhesus monkeys and chimpanzees.
• To investigate the segregation and compartmentalization of nerve fibers supplying these organs within the spinal nerve roots.

Main Methods:

• Stimulating electrodes were precisely placed on pelvic nerves (urinary bladder) and pudendal nerves (sphincters) in Rhesus monkeys and chimpanzees.
• Evoked responses were recorded from fascicles and rootlets of lower thoracic, lumbar, and sacral nerve roots under controlled conditions.
• Analysis focused on the amplitude and presence/absence of evoked responses to identify fiber conduction and segregation.

Main Results:

• Evoked responses varied significantly across different nerve roots, indicating differential fiber conduction.
• The presence and amplitude of responses correlated with the number of functional fibers within specific fascicles.
• Demonstrated segregation and compartmentalization of neural innervation to the urinary bladder and sphincters within spinal roots.

Conclusions:

• Nervous innervation to the urinary bladder and sphincters is segregated within the spinal nerve roots.
• The Rhesus monkey's bladder innervation originates primarily from sacral segments S1-S2, with minor contribution from L7.
• The chimpanzee's bladder innervation arises from sacral segments S1-S4.