The autonomic innervation of the human urinary bladder, bladder neck and urethra: a histochemical study.

The autonomic innervation of smooth muscle in fresh biopsy specimens of the human urinary bladder, bladder neck and urethra has been examined using specific neurohistochemical techniques. Acetylcholinesterase-containing nerve fibers have been demonstrated amongst the smooth muscle cells in all the biopsy samples. Enzyme-positive fibers formed a plexus, the density of which varied dependent upon the region from which the biopsy material was obtained. Catecholamine (noradrenaline)-containing autonomic nerve fibers were observed amongst smooth muscle cells of the vesico-urethra junction; other than for perivascular nerve plexuses. Noradrenergic fibers were absent from biopsy samples of other regions. Juxtamural, acetylcholinesterase-positive neurones were present in some samples, and a proportion of these cell bodies were closely related to noradrenergic nerve terminal regions. These findings are discussed in relation to those of other workers who have examined the innervation of the mammalian lower urinary tract.