Cholinergic innervation of the human urethra and urinary bladder: a histochemical study and review of methodology.

The present work gives a survey of the various methods for the histochemical demonstration of cholinergic nervous structures. The theoretical background and the specificity and sensitivity of the various methods are compared. It is concluded that the histochemical localization of the cholinergic transmitter metabolizing enzyme acetylcholine esterase still probably is the best method, giving a fairly good reflection of the distribution of cholinergic nerves. In comparison with the Falck and Hillarp technique for the demonstration of adrenergic nerves this method is much less specific and sensitive. The present work describes a rich supply of cholinergic nerves in the human urethra and urinary bladder in comparison with the scanty adrenergic innervation. Various functional aspects of the cholinergic innervation are discussed.