Gross and light microscopic features of the pelvic plexus in the rat

Nerves and major accessory ganglia of the pelvic plexus are described from 12 rats perfused with methylene blue. Nerves to ventral and dorsal aspects of the urinary bladder, and three groups of nerves to the penis (clitoris) are reported in detail. Myelinated nerve fiber diameters ranged from 1–10 μ in the pelvic nerve and 1–6 μ in the hypogastric nerve. When the pelvic nerve was deafferentated, by spinal ganglionectomy 28 days previously, 80% of myelinated fibers degenerated, and the remaining fiber‐size spectrum resembled that of the hypogastric nerve. Myelinated fibers ranged from 1–7 μ in nerves to bladder and 1–3 μ in the lateral nerve to the penis. Myelinated fibers were afferent in these nerves, since spinal ganglionectomy eliminated all of them. In the main nerve to the penis, myelinated fibers ranged from 1–8 μ in diameter. A few fibers remained after deafferentation by spinal ganglionectomy. Since these were preganglionic efferent fibers, they indicate that terminal ganglia were present in the penis. All myelinated fibers degenerated with transection of pelvic and hypogastric nerves. The mode diameter of myelinated fibers was 2 μ in all pelvic plexus nerves.