Structural changes in rat pelvic ganglia after penile nerve transection. All micrographs show immunostaining for VIP. In a, c and f the region of the ganglion closest to the penile nerve is at the bottom left of the micrograph. Panels b-g are from injured ganglia; all show ganglia ipsilateral to penile nerve transection except for panel f (penile nerve crush). a. Uninjured (contralateral) ganglion. VIP neurons are found throughout the ganglion but are clustered in the region near the penile nerve exit; VIP baskets are sparse. b. FluoroGold (FG) neurons retrogradely labelled from the penis (b1), immunoreactive for VIP (b2); the axon from one FG neuron appears to encircle an adjacent neuron (arrows). c. Numerous varicose VIP axons growwithin the ganglion ipsilateral to the injury, especially in theregion closest to the penile nerve (bottom left). d, e. Examples ofVIP baskets encircling pelvic ganglion neurons in the ganglion ipsilateral to penile nerve transection. f. Similar growth of VIP axon collaterals occurs after penile nerve crush. g. FluoroGold-labelled neurons surrounded by varicose VIP collaterals. Calibration bar represents: 100 μm (a), 50 μm (c, f), 20 μm (b, d, e, g) or 15 μm (g inset).