Origin and neurochemical characteristics of nerve fibres supplying the mammalian vas deferens.

Abstract

The present paper deals with the origin and neurochemical characteristics of autonomic postganglionic and sensory nerve fibres supplying the mammalian vas deferens. The vas deferens is innervated by postganglionic nerve fibres originating primarily from neurons in pelvic ganglia and, to a lesser extent, from neurons in the inferior mesenteric ganglion and sympathetic chain ganglia as well as by sensory nerve fibres arising from dorsal root ganglia. Three major populations of nerve terminals innervating the organ can be distinguished: (1) noradrenergic fibres; (2) cholinergic fibres containing vasoactive intestinal polypeptide, neuropeptide Y, nitric oxide synthase, and (in the pig) somatostatin, supplying particularly the lamina propria; and (3) non-noradrenergic, presumably sensory fibres, containing calcitonin gene-related peptide and/or substance P. The population of noradrenergic nerves is the most common. In the pig, it can be divided into three subpopulations: a somatostatin-containing, a Leu-enkephalin-containing and a subpopulation immunonegative to these peptides, in descending order of magnitude. In the rat, guinea-pig, and man, NPY seems to be the most common peptide occurring in the noradrenergic axons. In the pig, coexistence patterns of the substances existing within nerve fibres supplying the vas deferens blood vessels are clearly different from those found in nerve fibres innervating the organ wall. The majority of the noradrenergic fibres associated with blood vessels contain neuropeptide Y only, while non-noradrenergic perivascular nerves contain predominantly vasoactive intestinal polypeptide. The possibility of different sources of origin of the particular nerve fibre subpopulations supplying the mammalian vas deferens and its blood vessels is discussed.