The fine structure of autonomic neurons in the wall of the human urinary bladder.

Using fresh biopsy specimens, intramural ganglia of the human urinary bladder have been examined by electron microscopy. The fine structural features of these neurons were compatible with their classification as parasympathetic in type. In several ganglia, groups of neurons were observed lying in close apposition to one another without any intervening satellite cell cytoplasm. Apart from occasional septate junctions the apposing membranes lacked any specialisation. The majority of terminals occurring in association with these intramural neurons were axosomatic in location. The terminals contained numerous small agranular and occasional large granulated vesicles and structurally were presumptive cholinergic in type. Occasional axon varicosities packed with a heterogeneous population of small agranular vesicles, large vesicles of variable density and multivesicular bodies lay in close association with the ganglion cells. The functional significance of these morphological features in terms of ganglionic transmission has been considered.