Nerve endings in the urinary bladder of the cat

Abstract

Urinary bladders from mature cats, fixed in various degrees of distension, were studied with silver staining techniques under the light microscope, and with the electron microscope. Ganglia were located primarily in the adventitia, although small collections of perikaryons were located in nerves within the muscle coat. Large nerve trunks enclosed in perineural epithelium penetrated from the adventitia into the muscle coat, giving rise to smaller nerves which ran in the space between muscle fascicles. Small nerves entered each muscle fascicle, giving rise to final branches characterized by extreme tortuosity. There was less kinking and coiling of nerve fibers in bladders h e d in a more distended state. Encapsulated endings and myelinated fibers were scarce.Within a muscle fascicle, nerves were scant. Terminal branches intertwined among the individual smooth muscle cells as free nerve endings. Terminal axons continued to be ensheathed by Schwann cells. Neuromuscular synapses were characterizd by retraction of the Schwann cell from one side of the axon, presence of synaptic vesicles, and synaptic gaps of 400-600 A. Areas of close contact between flattened and interdigitating parts of adjacent smooth muscle cells were common. Membrane complexes of pinocytotic vesicles and endoplasmic reticulum were distributed around the periphery of individual smooth muscle cells. Smooth muscles cells appeared to vary in the density of their myofilament content.

A Decade of Experience with Electronic Simulation of the Micturition Reflex

“…This view derives from several lines of evidence: (a) testing of the origin of the excitatory junction potential indicates that in most cells it is electrotonically conducted from a nearby source [5,20], (b) the transmembrane impedance of a single cell is higher than the impedance measured between adjoin ing cells [54]. Similar electrophysiologic investigations of bladder muscle have been frustrated by the thick collagen cover surrounding muscle fasicles, (c) the re sults of morphologic investigations of bladder muscle are similar to vas deferens [33] and support this concept of spread of excitation. The ratio of innervated to nonin- nervated cells is low [33, 34J.…”

“…Nerve endings in bladder muscle [33,34] are similar to those in vas deferens [49] in that there are not specialized endings as in skeletal muscle and a single nerve fiber may innervate many muscle cells by axonal varicosities or synapses in passage. Axon varicosities consist of thinning of the Schwann layer and the appearance of medium sized agranular ve sicles ( fig.…”

“…[33]; (c) whether electrical stimulation of the detrusor muscle liberates the epinephrine stores which have been demonstrated by histochemical techniques in detrusor nerve networks [30] and if this release evokes hyperpolarization of the muscle cells [37], and finally (d) if bacteria release a relaxing substance affecting the urinary detrusor muscle in a manner similar to that in ureteral muscle [61].…”

“…Sensory nerve endings in bladder muscle are free and unspecialized [33,34]. They are located exclusively in the collagen bundles sur rounding the muscle and are bilaterally distributed [35].…”

Anatomy of the Lower Urogenital Tract

“…Postganglionic axons are nonmyelinated. Their terminal branches have preterminal and terminal varicosities (enlargements) that contain synaptic vesicles (Fletcher et al 1969). The vesicles release neurotransmitter molecules that diffuse variable distances and bind to receptors on myocytes.…”