ADRENERGIC NERVES IN CORPORA CAVERNOSA PENIS OF SOME MAMMALS

The corpora cavernosa et spongiosa penis from Rhesus monkeys, Cynomolgus monkeys and cats have been investigated by means of the method for fluorescence microscopical detection of catecholamines- and tryptamines according to Falck and Hillarp. In all species investigated the smooth muscle cells surrounding the sinusoidal cavities of the corpora cavernosa are densely innervated by varicose adrenergic nerve fibres, which form a typical autonomic ground-plexus. A superficial and a deep plexus have been distinguished, the former being composed of densely packed preterminal, ramifying bundles the latter consisting mainly of terminal varicose fibres. In contrast to this the corpus spongiosum - being mainly composed of collagenous and elastic tissue - receives only a moderate adrenergic nerve supply related to the small bundles of smooth musculature. Whereas arteries of the penis are characterized by a superficial adventitial fibre plexus, the greater veins of the penis are supplied by adrenergic fibre meshes which penetrate the media up to the limiting lamina elastica interna. In addition the paraurethral glands seem to possess a direct adrenergic innervation. According to microspectrographical results it is concluded that the transmitter is noradrenaline. This assumption is supported by the finding of relatively high amounts of noradrenaline in tissue pieces from the erectile tissue of four Rhesus monkeys: 0,67 μg/g (± 0,05). No dopamine or adrenaline have been detected. Scattered along the whole length of the urethral epithelium there occur yellow fluorescent cells morphologically resembling enterochromaffin cells. The fluorophore has the spectral properties of formaldehyde-condensed authentic 5-hydroxytryptamine. The possible role of the sympathetic noradrenergic innervation to the penis concerning the initiation and termination of the erection is discussed. © 1969 Springer-Verlag.