THE DISTRIBUTION OF INTRAMURAL NERVES IN URINARY-BLADDER AFTER PARTIAL DENERVATION IN THE FEMALE RAT

We evaluated the degree of neuronal plasticity following a partial den ervation of the rat urinary bladder. Using acetylcholinesterase staini ng we found that the postganglionic nerves from the pelvic ganglion re ach the intact bladder as 1-4 nerve trunks on each side, slightly vent ral and caudal to the ureteral orifices. Normally a few thinner nerves also reach the bladder posterolateral to the ureterovesical junction. The nerves ventral to the ureters run in the ventral longitudinal mus cle layer as well-defined trunks with a pattern that does not differ m uch from one animal to another. The nerves reaching the bladder dorsol aterally innervate the dorsolateral aspects in a more irregular fashio n. Some anastomoses are found across the midline between nerves from e ither side. This nerve pattern is already in place in newborn rats. Af ter removal of the pelvic ganglion on one side in the adult rat the ip silateral ventral nerves rapidly degenerate, whereas some dorsolateral nerves usually survive. Axons from the intact ventral nerves can be s een crossing over to the denervated side in the anastomoses. After 13 weeks the surviving Ventral nerves, which normally run at some distanc e from the Ventral midline, now pun in the midline with equal amounts of ventral longitudinal muscle on either side, and with their branches evenly distributed to both sides. The same pattern is seen after 27 w eeks. Unilateral ganglionectomy in 3-week-old rats leads to the same c hanges in nerve distribution as in the adult rat. We conclude that the re is a high degree of plasticity in the bladder innervation following a partial denervation, and that this plasticity includes the distribu tion of its main intramural nerve trunks.