Peptidergic innervation of the human testis and epididymis.

Neuropeptidergic innervation of the human testis and epididymis was investigated by immunohistochemical methods. The innervation of the epididymis was more dense than that of testis. In the testis only tyrosine hydroxylase- and neuropeptide Y-positive nerves could be found between seminiferous tubules and around blood vessels. In the connective tissue capsule of the testis also small calcitonin gene-related peptide- and metenkephalin-containing nerve fibres were seen. The epididymis was densely innervated by nerve fibres immunoreactive to tyrosine hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, calcitonin gene-related peptide, galanin, peptide histidine isoleusine and substance P.