Ultrastructural study of the autonomic innervation of the detrusor muscle in the wall of the urinary bladder of mice

ABSTRACT

Fifteen adult mice were used to study the fine structure of the intermuscular axon profiles in the urinary bladder of mice. Tissue samples were taken from the dorsal wall of the bladder and processed for examination in a transmission electron microscope. The muscle coat possessed an extensive plexus of nerve fibers, which were mostly motor in nature. Most of such motor nerves occurred as non-myelinated vesicle-packed axonal varicosities with a neurilemmal cell covering. Single axons were not infrequent. The vesicles were of two types, small agranular type and large with a dense central core one. The latter type occurred in relatively high numbers as the small clear vesicles. Such large granulated vesicles could be considered as the storage sites of neuropeptides in cholinergic nerve terminals