Noradrenergic and peptidergic innervation of the testis and epididymis in the male pig.

This study was designed to investigate the distribution of noradrenaline (NE)- and peptide-containing nerves in the testis of the boar. Testes, as well as caput and cauda epididymides from five 5 week-old and 3 adult boars were sectioned and immunostained with antisera to tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (D beta H), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), substance P (SP), calcitonin gene-related peptide (CGRP), Leu-enkephalin (L-ENK) and somatostatin (SOM). In addition, double-labelling immunofluorescence method was used to disclose the pattern of co-existence of these substances in the nerve fibres. The most abundant innervation was found in the cauda epididymidis, and the density of the nerves distinctly decreased towards the caput epididymidis. The testicular parenchyma and caput epididymidis was supplied with very scattered TH-, D beta H-, NPY-, VIP-, SP-, CGRP-, L-ENK- and SOM-containing nerve fibres. The present study has demonstrated for the first time the existence of CGRP, L-ENK and SOM in nerve fibres innervating the testis of a vertebrate species. Different subpopulations of nerve fibres, including TH+/D beta H+, D beta H+/NPY+, D beta H-/NPY+, D beta H+/NPY-, D beta H+/VIP+, D beta H-/VIP+, D beta H+/SP+, D beta H-/SP+, D beta H+/L-ENK+ D beta H-/L-ENK+, D beta H+/SOM+ and D beta H-/SOM+, were localized and documented.