Intrinsic neuromuscular defects in the neurogenic bladder: VIII. Effects of unilateral pelvic and pelvic plexus neurectomy on ultrastructure of the feline bladder base

It has been shown previously that unilateral parasympathetic decentralization of the feline bladder by sacral ventral rhizotomy results in early degenerative and eventual regenerative ultrastructural neuromuscular changes in the bladder base. The present study was conducted to define the effects of unilateral parasympathetic decentralization by pelvic neurectomy and postganglionic “denervation” by pelvic plexus neurectomy on the neuromuscular ultrastructure of the feline bladder base. Eighteen sexually mature male cats were used. Three cats provided the control material; six cats underwent unilateral pelvic and nine unilateral pelvic plexus neurectomy. Bladders were collected for study 2, 3, and 10 weeks following the former and 1–4 days, 3 weeks, and 7–12 weeks following the latter procedure. Samples from both the neurectomized and the intact sides of each bladder were obtained for electron microscopic study. The ultrastructural neuromuscular changes observed after pelvic neurectomy were identical to those previously described following unilateral sacral ventral rhizotomy, except for early developing and persistent, widespread degeneration of myelinated axons in the former model. As in the rhizotomy model, there was cholinergic axonal regeneration, adrenergic hyperinnervation, and a prominent population of probable copeptidergic axons in long‐term samples of the bladder base following pelvic neurectomy. In contrast, pelvic plexus neurectomy (a postganglionic “denervation” procedure) resulted in early developing and persistent degeneration of all axons in the bladder base: i.e., myelinated, cholinergic and adrenergic, with long‐term hypoinnervation by both cholinergic and adrenergic neural elements. Our observations indicate that two forms of the experimentally induced lower‐motor neurogenic bladder can be distinguished ultrastructurally.